GMT400 frame styles

[DieselDetroit]

Hey guys, I had a general question about the actual truck class and types

I have a 1995 6bolt light duty diesel 4x4 but it's s 3/4 ton. I'm wondering if my frame is different from the heavy duty diesels (with 8bolt rims, 1tons)

Also, my pop in law has a 5 bolt, 2wd 1/2 ton diesel, is that an even lighter frame?

I just want to know for informations sake. I've seen some 1/2 ton suburbans with 8 bolt wheels and cab markers, and they seem tougher than my 3/4 ton diesel

I was also wondering if there was an all encompassing classification chart with all the different frame and duty ratings.



Thanks boys!


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[phule]

I believe 2wd and 4wd frames are diffrent. They dont make 8lug 1/2 ton burban but the do make 3/4 ton 8 lug burbans. Also 1 ton frames are greatly different than your ld 3/4 ton.

Adam

 

[great white]

Well, i'll address the 4x4 question first.

The 1500 frames are all the same (except for length in RC, EC, SB,LB, etc). Diesel or gasser, same.

The 2500 (8600 GVWR, or 8 lug if you prefer) and 3500 frames are the same: diesel or gasser. Same exception for frame lengths for cab and box configuration.

Many guys will say the are the same strength wise, but that is incorrect. They have the same steel strength rating but the 2500/3500 have a higher modulus than the 1500. They also have the bigger front differential (which changes the front frame bracket geometry).

The "LD 2500" throws a bit of a curve, in that it is a 1500 frame with the bigger rear axle and suspension (springs). The front differential is the smaller 1500 diff and the frame is built for that.

The 2wd trucks follow the same pattern as the 4x4 trucks, except they are 2wd in the front frame.

Frame do not interchange between 2wd and 4x4 because of the front frame differences.

The 3500 HD is in a class all its own and is "radically" different from all the others.

Suburbans I won't comment on because I am not as familiar with them. They're almost like vans in my opinion as they seem to have weird combinations of parts compared to pickups. The vans were all weird bastardizations of parts combinations...

 

[RyanMerrick]

Well, i'll address the 4x4 question first.

The 1500 frames are all the same (except for length in RC, EC, SB,LB, etc). Diesel or gasser, same.

The 2500 (8600 GVWR, or 8 lug if you prefer) and 3500 frames are the same: diesel or gasser. Same exception for frame lengths for cab and box configuration.

Many guys will say the are the same strength wise, but that is incorrect. They have the same steel strength rating but the 2500/3500 have a higher modulus than the 1500. They also have the bigger front differential (which changes the front frame bracket geometry).

The "LD 2500" throws a bit of a curve, in that it is a 1500 frame with the bigger rear axle and suspension (springs). The front differential is the smaller 1500 diff and the frame is built for that.

The 2wd trucks follow the same pattern as the 4x4 trucks, except they are 2wd in the front frame.

Frame do not interchange between 2wd and 4x4 because of the front frame differences.

The 3500 HD is in a class all its own and is "radically" different from all the others.

Suburbans I won't comment on because I am not as familiar with them. They're almost like vans in my opinion as they seem to have weird combinations of parts compared to pickups. The vans were all weird bastardizations of parts combinations...

^Exactly. The light duty six lug 2500s have 1500 frames, they're kind of the oddballs in the lineup

 

[DieselDetroit]

Is there a chart or something somewhere?

So my light duty 2500 diesel has the same frame as a 1500 gasser? But I can tow more :0?

My gf gas a 1500 Tahoe 2dr and mine is an ecsb 2500 diesel. Pretty much the only difference is how much I can tow because of my tranny but other than that, it's the same

We are planning a trip soon and trying to figure out who can tow more

I have a 4l80e and she has a 60 with a 350, so I'm thinking that might be the limiting factor. Frame wise they are the same, just different power plants


Previous owner had my truck set up for a 5th wheel that worries me a bit

 

[someotherguy]

If you take a peek at each weight capacity you will also find small differences like gussets on spring hanger brackets for the heavier trucks, etc. More than a few tiny differences.

Richard

 

[great white]

Is there a chart or something somewhere?

So my light duty 2500 diesel has the same frame as a 1500 gasser? But I can tow more :0?

My gf gas a 1500 Tahoe 2dr and mine is an ecsb 2500 diesel. Pretty much the only difference is how much I can tow because of my tranny but other than that, it's the same

We are planning a trip soon and trying to figure out who can tow more

I have a 4l80e and she has a 60 with a 350, so I'm thinking that might be the limiting factor. Frame wise they are the same, just different power plants


Previous owner had my truck set up for a 5th wheel that worries me a bit

Towing capacity is more than just a frame rating.

It's a combination of axles, brakes, suspension, engine, transmission, cooling, etc....

For example: in the same year as my 98, a 454 truck can tow 10,000 lbs where my diesel is only rated for 8500. That's the same truck, equipped the same way, same transmission, same axles, same gearing, with the same options except for the 6.5 diesel.

The limit on the towing rating can be any single component or the specific combination of components.

Go with what the OEM rates them for.

Your 2500 may very well be able to handle a 5th wheel, depending on what the pin weight and total weight of the trailer is/was. Even if it is over the weight rating, it's not like it's going to snap in half or flip off the road a couple hundreds pounds over. But what will happen is the brakes will fade sooner on a hill, the suspension will duck weave and porpoise more than it should, the steering will be lighter than it should, etc.

Just so we're clear here: I absolutely do not recommend towing heavier than the OEM rating.

In my experience, people tend to overload the factory rating rather than under load it. Problem is, most just don't know what their trailer weighs because they never take it to the scales. Same story goes for the weight of the truck. Unless you scale it all, you don't know what it really weighs.

99% of the time, OEM stated weight numbers are usually grossly under the actual trailer/vehicle weight as it sits ready to roll.

It's how they can say that BS line to sell more trailers/trucks: "half ton towable"

BS

 

[eric.s.t]

i really don't understand this ... How does a 6 lug pick up with a 1500 frame end up being a light duty 2500? Wouldn't it just be a...1500...? Just like, why do they make a "1500HD" not sure if the available in the OBS, but im wondering for example the NBS, 1500Hd has a 6 litre, 8 lug axles, and some seem to have the 2500 frame? So... what is it, weaker suspension? Why would you want a "1500HD" that in theory (in my mind lol) can tow more because the gearing/motor/brakes/axles/etc, but cant actually hold it because the suspension isn't strong enough... hmm im just stumped on these options!

 

[great white]

i really don't understand this ... How does a 6 lug pick up with a 1500 frame end up being a light duty 2500? Wouldn't it just be a...1500...? Just like, why do they make a "1500HD" not sure if the available in the OBS, but im wondering for example the NBS, 1500Hd has a 6 litre, 8 lug axles, and some seem to have the 2500 frame? So... what is it, weaker suspension? Why would you want a "1500HD" that in theory (in my mind lol) can tow more because the gearing/motor/brakes/axles/etc, but cant actually hold it because the suspension isn't strong enough... hmm im just stumped on these options!

It's just GM's F'd up way of doing things.

There never really was a LD/HD thing (or a "heavy half" for that matter, that was prior to the GMT400 chassis).

GM went by weight ratings. This LD/HD thing in the GMT400 platform is the same as the OBS/OOBS/NBS/NNBS internet bullspit.

However, GM started actually using the "HD" designation in the later model year trucks (IE: not the GMT400) and they actually did use heavier frames and whatnot. Whether or not there is commonality between the later styles in the 1500HD/2500's I don't know. Not familiar with those chassis.

And just to complicate matters, Gm turned around and used LD in the owners manual for many years for GMT400's below GVWR of 8500 lbs and HD for vehicles 8600+ GVWR.

Then toss in vehicles above 10,000 lb GVWR are in a different class again....

 

[eric.s.t]

It's just GM's F'd up way of doing things.

There never really was a LD/HD thing (or a "heavy half" for that matter, that was prior to the GMT400 chassis).

GM went by weight ratings. This LD/HD thing in the GMT400 platform is the same as the OBS/OOBS/NBS/NNBS internet bullspit.

However, GM started actually using the "HD" designation in the later model year trucks (IE: not the GMT400) and they actually did use heavier frames and whatnot. Whether or not there is commonality between the later styles in the 1500HD/2500's I don't know. Not familiar with those chassis.

this all makes my head hurt... why cant they just make a 1500, 2500 and 3500... people who want a pickup for a grocerie getting, use the 1500... the 1500 will still haul! Just give the options motor/gearing/tranny... and then those who want something bigger buy the 2500 or 3500... i mean it sounds so simple, its not going to make any more sales! If the guy in the market for a truck, its the 1500HD vs the 2500 that's gonna make or break the deal! i think... ? sorry guys...