For years, the Ford Motor Company has held the crown of having the burliest diesel in America. The high-output version of the 6.7-liter Ford Power Stroke V8 with 500 horsepower and 1,200 lb-ft of torque beat the rest of Detroit in power, and not exactly by a small margin. Today, General Motors has announced the final answer in diesel pickup truck engines. The new 8.3-liter Duramax V8 diesel engine isn’t just the biggest diesel fitted to a mass-production pickup truck, but it puts Ford into a solid second place. Yet, there’s one metric that, despite GM’s best efforts, it could not beat Ford on.
The rumor mill has been busy printing out speculation about the future of Duramax diesel engines for longer than two years now. Back in January 2024, the Fast Lane Truck (TFL) reported that “a source with knowledge of GM’s internal powertrain development alerted us to a new, bigger, and far more potent powertrain about to emerge as the new king of the hill: a massive, 8.3-liter beast.” There was a lot of skepticism following the publication of TFL‘s news, with some, including GM enthusiast blogs, concluding that chasing best-in-class power numbers was more of a Ford thing. TFL nicknamed the project “Megamax” in its coverage, which was fitting.
As it turns out, TFL was right from the jump. While GM did not confirm to TFL that it was designing a new, bigger Duramax diesel engine, it was secretly working to create the very engine that someone leaked to TFL. The real engine does not make 600 horsepower as originally speculated. Instead, it still puts out more than enough thoroughbreds and twist to unseat the Blue Oval from its long-held throne. In the process, it has also built an engine that, so far as I can tell, is the largest diesel engine ever fitted to a mass-market production diesel pickup truck in America.
The Rumor Mill’s Rumored Mill
The Fast Lane Truck got Chevrolet Silverado and GMC Sierra fans excited for what sounded like the impossible. In 2024, TFL explained the rumor they heard and why it was a big deal:
As for the headline specs, we’ve been told this new 8.3L diesel engine (which we are calling “MegaMax” — there’s no indication that’s the name GM has in mind for it) puts out up to 600 horsepower and up to 1,200 lb-ft of torque.
For reference, the current 6.6-liter L5P Duramax turbodiesel available in 2024 and newer Chevy Silverado and GMC Sierra HD models manages up to 470 horsepower and 975 lb-ft of torque, according to SAE J1349 power and torque certification measurements. If the automaker does see such an engine through to serial production, GM would leapfrog ahead of Ford, whose 6.7-liter Power Stroke diesel V8 cranks out 500 horsepower and 1,200 lb-ft of torque in its high-output form. Despite packing two fewer cylinders, the 6.7-liter H.O. Cummins in Ram’s heavy-duty trucks produces 420 horsepower and 1,075 lb-ft of torque.
Ram’s heavy-duty pickup trucks have since upgraded to 430-horsepower mills, but GM’s L5P Duramax has stayed the course with its output. This put General Motors in a weird position in the diesel pickup truck market. It couldn’t touch any version of the 6.7-liter Ford Power Stroke V8, and only bested the Cummins on horsepower.
Yet, understandably, some didn’t believe that GM would go as far as to make a mammoth diesel to rule them all. While the 6.6-liter Duramax V8 was technically third in its field, it wasn’t like the Silverado and the Sierra were suffering. They still benefited from a 36,000-pound towing capacity in a properly equipped truck pulling a fifth wheel or gooseneck trailer. Sure, this was 4,000 pounds short of the Ford F-450’s headline-grabbing 40,000-pound limit, but 36,000 pounds is still tons of weight for a pickup truck to haul. For reference, a Ram 3500HD pickup truck could tow up to 36,610 pounds with a regular cab, a 6.7-liter Cummins straight-six, and a long bed. The best towing configuration for a Ford F-450 is similar.
Apparently, General Motors did not agree with the notion that the L5P Duramax V8 was enough by itself, because its DMAX division has taken the biggest of swings by crafting a whole new 8.3-liter V8 diesel engine from a clean-sheet design.
The ‘Mongoose’ 8.3-Liter Duramax Diesel V8
General Motors says that the new engine, codenamed “Mongoose,” was designed from scratch in-house specifically for the heavy-duty pickup truck market. The 8.3-liter engine sports a compacted graphite iron cylinder block, a forged crankshaft, forged connecting rods, and steel pistons. GM says the engine’s new architecture features an integrated intake, an “advanced combustion system,” and crankshaft isolation for reduced noise and vibration. It also features a compact dual-stage air-to-water charge cooler, a high-efficiency variable-geometry turbocharger, and upgraded engine cooling.
Backing up all of these goodies is an Allison 10L1000 10-speed transmission, an exhaust braking system, and a diesel aftertreatment system that’s supposedly fit for a truck that lives a hard life of towing and hauling. It all adds up to a behemoth 8.3-liter diesel V8 that pumps out 555 horsepower and 1,230 lb-ft of torque. For those of you counting, this readily beats Ford’s best and leaves Ram in the dust.
It also has the distinction of being the largest diesel ever offered in a mass-market pickup truck in America. I’ve done some digging, and the closest that I could find was Ford’s own legendary 7.3-liter Power Stroke V8 of the 1990s and the 2000s. To be clear, the semi-tractor market has had much larger mass-produced V8 diesels, like the 12.1-liter Detroit Diesel 8V92 and Scania’s whole range of V8 diesels, which reach as high as 770 horsepower and 16.4 liters of displacement. The 18-liter Caterpillar 3408 is another seriously chunky V8 diesel.
Historically, however, the diesel pickup truck market in America has had smaller diesels than their big rig and construction machinery counterparts. So, a mega version of the Duramax is pretty wild. As for that name, well, that one is just GM picking its target. The mongoose is a predator to the scorpion, and “Scorpion” was used as Ford’s codename for its 6.7-liter Power Stroke engine.
General Motors says the new engine is a rather huge deal. The automaker invested $920 million into its Duramax diesel program to enable it to create this behemoth, which will be built in the GM DMAX complex in Brookville, Ohio. In describing the new engine, GM says that “The all-new available diesel is GM’s first clean-sheet HD V8 designed, developed and manufactured in-house for heavy-duty pickup applications.”
As I have written in the past, the Duramax diesel dates back to a partnership between General Motors and Isuzu that minted its first production engines in 2001. What’s interesting is that some sources say that the L5P Duramax engine, which went into production during the 2017 model year, is a clean-sheet design. Other sources say that it’s merely a “near clean-sheet” design. GM’s claim would seem to support the idea that previous Duramax diesels at least had some of the original GM-Isuzu DNA still left in them.
The new engine isn’t all that’s coming for 2027. GM says it has announced the heavy-duty pickup truck segment’s first electric power steering system for its new Sierra and Silverado pickups. According to GM, this new rack and pinion system provides 30 percent more steering power than previous hydraulic systems, while also offering fine-tuning through drive modes, improved on-center feel, and less kickback on rough surfaces. The electric power steering system is reportedly also built to take some hits and survive the worst that America’s saltiest roads could throw at it.
Another new feature is an electronic brake-boost system, which GM says is another first in the heavy-duty pickup truck market. The new trucks will come with four-piston calipers up front, which will chomp on 14.6-inch rotors. The big brakes are said to have a better thermal capacity, while the electric brake booster reduces pedal travel, makes pedal feel more linear, and allows for better integration into active safety systems like adaptive cruise control and automatic emergency braking. While perhaps not of the most importance in a heavy-duty pickup truck, the electric booster also shaves some weight compared to a hydraulic version.
Finally, off-road versions of GM’s heavy-duty pickups, namely the Chevrolet Silverado ZR2 and the GMC Sierra AT4X, will be getting a new Terrain driving mode that will allow for one-pedal off-road driving. While this feature is new to GM, its competition, like Ford, has had a sort of off-road cruise control in heavy-duty pickup trucks for years.
For those who don’t like diesel, General Motors says it’s also updated the 6.6-liter gasoline V8 for 2027. GM says that the updated engine “gains horsepower and torque, with improved low-end pull and updated emissions hardware supported by a new Turbo-Jet intake manifold, revised lubrication system, engine-mounted oil cooler and digital oil-level display.”
GM neglected to say just how much horsepower the updated 6.6-liter gasoline V8 will make. It also doesn’t say if the digital oil-level display means that the engine won’t have a dipstick. I have reached out to General Motors for clarification on these figures.
Ford Still Beats GM In One Metric
The big number is towing. General Motors says that properly equipped 2027 Chevrolet Silverado HD and 2027 GMC Sierra HD trucks will have 20,000 pounds of conventional trailer towing capacity, and up to 38,000 pounds of gooseneck towing. The 20,000 figure is unchanged from the current-generation GM HD pickups, while the latter number is a 2,000-pound upgrade. Notably, this means that, despite having the biggest engine in the business, GM’s trucks technically still tow less weight than the 40,000 pounds that can be hauled by a properly equipped Ford Super Duty.
Still, the gap is now only 2,000 pounds, and I’m sure there will be plenty of truck buyers who won’t care just so they can say they bought the biggest, baddest, and most powerful diesel on the market. Also, the Ford’s win is only a technicality, as it’s on the F-450 chassis. GM doesn’t sell trucks with pickup beds past its 3500 class. However, the towing upgrade does mean that the Chevrolet Silverado 3500HD and its GMC twin can now haul the same weight as an equivalent Ford F-350.
But why? In a world where diesel is seen as old news, and high diesel prices break records, why would GM introduce this colossus?
As Automotive News explained recently, it’s because General Motors sees a future in diesel and is doubling down on the technology in both light-duty and heavy-duty pickups:
“It’s not one engine for everybody,” GM President Mark Reuss said during a media event at the company’s engine plant here. “It’s the freedom to choose the engine that fits your work, lifestyle and priorities.”
For Silverado and Sierra buyers, GM sees its diesel powertrain as having some advantages over a hybrid option, including driving range. The redesigned pickups’ Duramax engine allows more than 900 miles of highway driving on a 34-gallon tank. “If you look at the performance and efficiency but also raw performance and range, hybrids really don’t do it,” Reuss said. “It’s a bit different adding a hybrid system to an existing powertrain and trying to get the efficiency out of it like that.”
“Different customers need different combinations of capability, range, affordability, towing confidence and convenience,” Reuss said. “Our aim is to meet them where they are.”
As a note, GM was still being secretive about this new engine when that Automotive News article was published. The range figure stated above is for the Duramax 3.0-liter engine.
Additionally, as General Motors says, over 60 percent of its heavy-duty truck buyers opt for diesel, and it also sells the most diesels in the heavy-duty pickup truck segment. To GM, making a herculean V8 diesel just cements its place in the diesel world even further.
So, while Ford, Toyota, and Ram commit to hybrids, General Motors is going the opposite direction. It remains the only automaker in America with half-ton diesel pickup trucks on the market. Now, this monolith of an engine is going to be a monument to oil-burning power.
As for the awkward situation of how this engine is going to launch into a market with historic diesel prices, it’s pretty clear that General Motors has been working on the Mongoose for at least a couple of years. Today’s diesel prices are an unfortunate coincidence.
If diesel prices aren’t stopping you from getting a new diesel truck, and you want the one with the largest lump of diesel under its power barn, GM says that its 2027 heavy-duty pickups will ship to dealers late this year. Should you be one of those who go all-in on diesel, you’ll be getting an engine with a displacement so huge that each cylinder has more than the volume of one of the engines out of my Smart Fortwos.
That’s just silly, and honestly, I’m here for it. Only General Motors could have concocted an idea this crazy. In a world of hybrids and electric cars, the General is making a huge bet on diesel. It’s even wilder to think about when you realize that GM could have made an extended-range electric truck, or maybe even a diesel-electric hybrid. But nope, it instead decided to make a hilariously huge lump of diesel power.
Will GM’s bet pay off? I have no idea. I know I shouldn’t like this idea, but I’d be lying if I said I didn’t want to be the first journo in line to test it.
Top graphic images: GM
I think many of the negative comments on here forget that a good portion of the trucks sold with these big diesel engines are for people to make their living. Sure, it seems like one upmanship and marketing for the big three to constantly leap frog each others numbers. But there are many small business owners that make their truck purchase decisions based on exactly those figures and how it best applies to their business. For every bro dozer clown with nary a scratch on their coal rolling Carolina squatting 3500s, there are many contractors or landscapers who rely on these work horses to pull them and everything else to work every day. And as far as the cost of diesel, most of them, or, I should say, us, don’t care. Wether its 100, 200 or 300 a week in fuel, its a rounding error in the scope of the business, and it will just be passed on to the customer anyway. Like everything else you buy in a store that was delivered by a truck. Good for GM for this monster engine.
For scale, I use a piston from the Caterpillar 3400 series as a coffee table.
I could mow down so many more schoolkids that I can’t see while driving it with 1230lbft
i’ll take the under 10k miles before self detonation.
The 8.3L Duramax is big news… but I see bigger news coming from this info.
I think I see the plan here, and GM will be in a better position to do this vs Ford and Ram in about 12-18 months time (because both of those have solid axles, which adds difficulty.
Because the steering/brake updates allows GM to enable the HD trucks to have Supercruise and Supercruise while towing. If I was using an HD truck to tow a lot, hands down I’d go GM when they release this feature. Once you have hands-free driving in your life… I hate to say it… it’s really hard to buy a new vehicle without it.
You must live in a city. Also, what is the issue with solid axles in an HD truck exactly? I have both, and the IFS in my GM is a serious limitation. My plow weighs 1100lbs and the IFS is massively beyond it’s rated capacity. I only use it to plow my drive and common road with neighbors, but would never attach it for use on a public road.
I don’t rely on self-driving in cities much, because of certain situations where it doesn’t really know the nuance (i.e. narrow roads in old neighborhoods, etc..).
Where I think self-driving really helps is in more rural areas, where I used it on county roads, highways, etc…it makes 6 hour road trips feel more like 3 hours… and that’s the real benefit.
What I mean about the solid axle vs IFS situation doesn’t have to do with weight capacity (for a plow, which I agree with you). When you have an IFS you can use a rack/pinion steering system much easier vs a solid axle, and if you have a rack/pinion it can be fully electrified easier (like all cars have now). Now.. because a rack/pinion provides more accurate steering vs recirculating ball…now you have a more accurate input/output for a self driving computer to work with. If you have a current ram HD with the extra steering assist option, that uses an electric motor AND a traditional hydraulic power steering system… so two systems. Meanwhile the electric rack for GM has one power assist system…
In a nutshell:
Electric assisted rack & pinion means better steering accuracy (for supercruise) and possibly better cost at scale (although that part could be wrong). Electric rack would also enable automatic trailer backing (for those who can’t) and hybridifcation of the HD trucks later…
I appreciate the elaboration on a IFS with respect to electric steering. As for self-driving, put me in the luddite category, especially when I am towing heavy. I am looking as far ahead as I can. When this permits, I may do far in excess of the posted speed limit. But looking ahead has prevented a speeding ticket for almost 35 years. I still enjoy the driving aspect of driving.
I applaud people like you, we need more truck drivers like that.
I’m sick of folks who I see (a lot of) on I25/I70 in Colorado who aren’t paying attention while towing a 5th wheel. And no it’s not just someone from XYZ state… it’s people from all over doing this poorly.
Agreed on this. EPS availability on the HD platform is a pretty big update, and both Ford and Ram would need big core vehicle architecture updates to compete. If they get SuperCruise going, competition is WAY behind on a similar offering. There is some autonomous research offerings in the Class 8 segment that may trickle down, but I don’t see those being off the shelf available nearly as quickly as SuperCruise, which is already in the market on a lot of GM products.
Yeah lots of Autonomous interest in Class 6-8 trucks… and that is coming sooner than people think.
You know what electric power steering and electric brakes also allow you to do that a hydraulic system won’t… Drive with the engine off…
Exactly
I see a lot of general negativity in the comments, and the reasoning isn’t lost on me here, and look-I’ve never owned a diesel, nor will I probably ever. The heaviest I tow is about 3,500 lbs worth of firewood, and I do that with a V6 Wrangler. So don’t come at me guys…….
But dude.
Dude.
This engine is sick, and I want to hear it, look at it, and drive it.
You have to think of the levels of performance these engineers are squeezing out of some flammable oil exploding.
It’s just mind blowing to me.
Watch the TFL video interview. This engine is about lowering combustion temperatures while maintaining power. They are preparing for future emissions regulations. Specific power levels are below their competitors. Looks like a well-thought out design to me.
Oh I have no doubt the displacement itself is a protection of power output while keeping reliability and emissions in check.
Like Cummins theoretically is doing with thier theoretical, rumored, definitely-not-at-all-being worked on 7+ liter Cummins.
I think the HO powerstroke may be at the absolute limit of what is capable with 6.7 liters and thier longevity goals (though itself so far has proven to be a very reliable and long-lived engine) and the only way to go forward and push the envelope is probably to go up in displacement.
Nothing theoretical about the Cummins B7.2. It is real and has HP ratings from 240 hp to 340 hp and torque from 650 to 1,000 lb-ft. That is the commercial version.
Agree. I thought this was an automotive enthusiast site.
Ahh, so goes the internet comments section. Some people think EVs are an affront to life, liberty, and the pursuit of happiness, some people think anything bigger than a 1/4 ton truck is the same thing.
90% of us fall in the middle and are reasonable folks, it’s just the other 10 percent are very passionate about making thier opinions known.
Honestly, I don’t know that there’s anything wrong with that.
We can be automotive enthusiasts and still think that the HD truck one upmanship from the big three is pointless and stupid.
Sure. I guess I’m more interested in the engine and not what it’s going in.
I really can’t see this going into a commercial vehicle. It is way too overstressed for that.
Why not? Just “de-tune” it (reduce fuel and boost etc…
It’s exactly what is already done. The Cummins ISB in the Ram goes into a million different applications including commercial vehicles just at different “tunes”
The commercial B6.7 is different than the one in the Ram. It isn’t just tuning. Different block, valvetrain, pistons….
Commercial version weighs about 150 lbs more dry.
Why can’t the same be done for this engine? I’ve simplified my example for the sake of brevity and the nature of short hand forum medium. I guess if you are saying that this exact spec/build of the engine won’t make it into commercial then I agree.
GM certainly could make basically a completely new engine that just shares the displacement to be used in some future commercial vehicle. The problem is that they would have to foot the bill themselves.
Ram paid Cummins to design, develop, tool, and manufacture the engine that goes into the Ram.
Anyone know if the lower power/liter is going to let them pass emissions easier, or have fewer interventions?
Seems to be the case. 2027 brings stricter NOx emission regulation and lower power/liter = lower combustion temperature = lower NOx.
Edit: they actually make the same ~148 ft-lb per L so maybe not. Need the crank throw and cylinder diameter to actually back into the cylinder pressure and thus temperature. I haven’t seen any internal engine specs released.
That is one way to approach the EPA 2027 NOx requirements. The other way is what VW did (International in the USA) and eliminated EGR altogether, stop trying to control NOx in the engine, run the exhaust temp hot to keep the aftertreatment temps up and crank up the DEF injection.
Indeed. I think the issue is SCR can only reduce NOx by 95% at best and the new regulations are so tight you wouldn’t reduce the NOx enough to meet with just this strategy.
For 2027 From google:
NOx limit
The standard drops from 0.2 grams to as low as 0.035 grams per brake horsepower-hour.
VW is purposely running their in-cylinder temps high which increases NOx. They are then using a dual-stage SCR to reduce NOx in the aftertreatment.
Dual-stage SCR may be conversion efficient enough for this strategy to work.
Yay! A new ‘my truck’s engine is bigger than your truck’s diesel engine’ fight!
Just in time for $7/gallon diesel fuel.
That’ll be $230 to fill up your new truck.
kthxbai
should be just enough to get you to the Cabela’s parking lot.
“The ‘Mongoose’ 8.3-Liter Duramax Diesel V8″
They should call it the ‘Douche Bro Duramax V8”
Because that’s who this engine is for. There is no way someone “needs” this level of power in any consumer-grade application.
And unless GM is planning on getting back into the Class 8 commercial truck segment, this engine is completely pointless… except for selling to Douche Bros.
GM dropped out of the Class 4 segement (4500 – 6500), but GM Authority says that this engine was partially designed with a reintroduction into the Class 4 through Class 7 segment in mind.
Imagine if we put this much into technology for small displacement motors to get really good MPG instead of massive power.
GM’s truck engines are generally class-leading in fuel economy too (real world, not necessarily EPA). A lot of people get 30+ MPG out of the small diesel. The 2.7 in their half-tons is at or near best-in-class MPG (only Ford’s 2.7 is even competitive). Their V8s walk all over anyone else’s V8s in fuel economy. They are putting serious engineering into fuel economy, and they’re doing it in larger vehicles where it has the most impact.
We do?
I’ll leave the diesel commentary aside, but I am totally here for the Turbo Jet intake manifold on the 6.6L (er, 400 ci) gasoline engine, just on 1960s-style name branding alone.
Just a few decades ago we moved 80,000 pounds and more with 237 horsepower and just a 5 speed transmission. Looks like today’s wannabe truckers are so incompetent they need twice the power to move half the load!
Or a few decades ago, we could afford to pay a trucker to drive his 237hp rig at 20mph up a grade because he could pop a bunch of uppers and probably get to his destination 20 hours later if he didn’t fall asleep at the wheel enroute.
This 3500HD has more HP and Torque than any Freightliner M2 106 (Class 5-6) that you can buy today.
Let’s completely ignore the ability to move that 80,000 lbs at elevation and up a steep grade while maintaining 55+ mph and 99% reduced emissions.
Looking forward to seeing these with 2nd owners who add emissions delete kits, wide offset chrome wheels with low profile tires, and floor them through traffic to smoke out the streets and make the tail end wag like a Mustang trying make the Cars and Coffee Departure Hall of Fame.
Impressive engine for actual work, but I’d love for somebody to invent an ignition lock that can scan the IQ and emotional maturity of the driver and prevent the engine from.starting if it detects a dirtbag suburban redneck in the driver seat.
I’m feeling like the endgame for these trucks is something like:
Truck owner 1- “My Denali HD has more torque than a Kenworth!”
Truck owner 2- “Oh yeah, my Ford F250 has more power than two Freightliners!”
Truck owner 3- “But my HD Ram has a taller grill than a Mack! The hood doesn’t even fit under the garage door!”
Random wife- “Wow, I used my 30 year old Honda Fit to pick up 500 lbs of concrete yesterday, and parked it in the garage with plenty of room to spare to unload. When is the last time any of you used one of your trucks to do something like that?”
Silence
Wife- “Can any of you even lift a 75lb bag of concrete over your head, to load in the bed of your trucks?”
Silence
Wife- “Are your monthly costs to own one of these trucks less than my mortgage?”
Silence
Our family has an F-450 and uses much of that towing capacity for trailers over mountain passes. This new GM engine has my ears perked for how it behaves, and if the massive displacement means less DEF required.
Likewise we tow heavy in the Rockies so also use the power in our F-350. I am thinking larger displacement means lower combustion temps and cylinder pressures – this may drop or at least raise NOX and there for DEF consumption.
That’s exactly what it’s supposed to do. Run cooler, reduce NOx emissions and increase longevity.
Finally! I’ve always said these engines and trucks are just TOO DAMN SMALL.
Turbo jet intake . . . uhhh what? Yes, I know this question is about the gasser. But still. what is the marketing hoopla?
Just in time for $8 diesel. This will be flying out showrooms and into repo
I can almost imagine the GM execs knowing that they wanted to launch this engine, and watching the price of fuel just tick up and up over the last few months.
I’m not sure they could have picked a worse time to launch really, although who knows what next week will bring.
Does this mean that the Allison branded transmissions are sticking around?
https://www.theautopian.com/general-motors-and-allison-breaking-up-doesnt-mean-what-you-think-it-does/
Yep, they renewed their partnership or however it’s structured
GM Heavy-Duty Pickups Will Keep Allison Transmission Branding After All
“GM’s trucks technically still tow less weight than the 40,000 pounds that can be hauled by a properly equipped Ford Super Duty.”
Yeah but that’s compared to an F450 which (I say with only a little confidence) the average retail consumer really isn’t buying. The 450 is technically a medium duty truck.
My town has bylaws for commercial vehicle parking in residential areas, and the F450’s 9000lb weight wouldn’t tip it.
Ford does something weird with the F350/450. IIRC, the 350 has the higher payload capacity, the 450 has the higher towing capacity. Currently, the 350 has a max payload of up to 8000lbs, but “only” tows up to 38,600. The 450 max payload is “only” 6400, but tows 40,000lbs.
Ram and GM have a 4500, but it’s only sold chassis cab and commercial sales. F450 GVWR is right at the top of the class 3 segment, so still technically a consumer vehicle. Class 4- where the Ram and GM live, are medium duty commercial trucks. Apparently and weirdly, according to Google, if you buy a chassis cab F450, it’s fully a class 4 truck. Maybe because Ford sells it with a bed and nice interior, it keeps it’s class 3 status?
Yeah it used to be that an F450 was a chassis cab only, then at some point in the 2010’s maybe I saw one with a pickup bed. I aksed the owner if he’d made it and he replied no you can order one this way now. It was news to me.
But yeah there must be something going on with the ratings of the pickup F450 in order to squeak it in as a class 3. I wonder if the F450 chassis cab has different ratings? I’m guessing the retail F450 is aimed specifically at RV and horse trailer folk for fifth wheel duty.
Truck classes are based on GVWR not what is on the back of the truck
Light Duty:
Class 1 0 to 6,000 lbs
Class 2 6,001 to 10,000
Medium Duty:
Class 3 10,001 to 14,000
Class 4 14,001 to 16,000
Class 5 16,001 to 19,500
Class 6 19,501 to 26,000
Heavy Duty
Class 7 26,001 to 33,000
Class 8 33,001 to infinity.
I fully understand how the classes break down, but I’m wondering how a fleet spec F450 with a single cab and no bed is a class 4, but a civilian spec truck with fancy interior, a bed, and other accessories with a (presumably) higher curb weight can still be class 3 since curb weight factors into GVWR.
Ford can rate the GVWR at whatever they want; the curb weight only comes into play when calculating the resulting payload.
I *believe* the springs are in fact different between an F450 chassis cab and an F450 pickup, but the Class 3/4 distinction is mostly just a paper one in this case.
As V10 mentioned the manufacture can play with the payload rating when setting GVWR. There can be licensing reasons to do that.
With vehicles that tow there could be an incentive to lower the GVWR of some trucks to give more towing capacity before requiring a Class A CDL. A Class A is required if the GCWR is 26,001 or more and the trailer is 10,000 lbs or more. So dropping the GVWR of the truck from say 15,000 to 13,000 lbs would give the owner the option to pull a trailer rated at 13,000 lbs.
The typical truck with a bed isn’t going to have thousands of pounds in that bed so the manufacturer might bias the GVWR for towing. Someone that buys a chassis cab is likely going upfit that chassis with utility body or flat bed and carry a lot more on the truck itself so they need a higher GVWR.