by "Urambo Tauro" (urambotauro)
Published 12/05/2017 at 12:00
by "Urambo Tauro" (urambotauro)
Published 12/05/2017 at 12:00
Tags: platforms
; chassis codes
; gmt400
; chevrolet
; chevy
; gmc
; trucks
STARS: 1
I have a few ideas, but does anybody know for sure?
GMT400 of course refers to the ’88-’98(ish) body style pickups and related SUVs, and it’s a much better term than that “OBS” crap . Wikipedia and other sources mention a GMT480 that is “similar”. How so? What’s the difference?
Wikipedia’s GMT400 page
shows that there are several submodels that fall under the GMT400 series. For example, the Chevy Suburban is GMT410, but the GMC Suburban is GMT425. Could GMT400 be Chevy only, and GMT480 indicate the GMC version?
The ordering of the GMT4XX numbers is kinda throwing me off here. There’s a 410, a 415, and a 420 (all Chevys). Then there’s a 425 and a 430 (both GMCs). Then a 435 for Cadillac. I wouldn’t expect GMC pickups to have a number so far away from the rest. It’s as if 480 was meant to be something very separate from the standard offerings.
Could it be for the medium-duty Kodiak/Topkick commercial trucks? No, those would be GMT530 s. How about 3500HDs? Google tells me that those are actually GMT455s, a number absent from Wikipedia’s list.
Sure, there’s always a chance that Wikipedia was erroneously edited at some point. It’s apparently missing some information, and no sources are listed for any of these numbers. Maybe we need a more authoritative source...
Wait a minute, what about 4WD vs 2WD? Could 480 be there to differentiate 4WD from 2WD models, like the “K” and “C” designations do? Doubtful- there appears to be no such separation among Suburbans (unless there are even more GMT4XX numbers missing from the list).
And there are too many different cab/bed configurations for 480 to simply be a LWB version of the 400. So what does it mean?
EDIT: It might be worth mentioning that the GMT800 generation of trucks uses an “880” designation for HD models. However, the Suburban’s “830” designation doesn’t line up with the GMT400 generation.
The biggest clue that I’ve managed to dig up so far is an Automotive News article from 2000 that mentions the GMT480 as having been built alongside 450s (?) and 455s: [possible paywall alert]
If this information is accurate, it could be a big step towards solving this mystery...
"MasterMario - Keeper of the V8s" (mastermario)
12/05/2017 at 12:05, STARS: 1
You’re still in the rabbit hole!?
"Urambo Tauro" (urambotauro)
12/05/2017 at 12:06, STARS: 1
This has been on my mind for a long time haha. Too big of a tangent to include in that previous post.
"DC3 LS, will be perpetually replacing cars until the end of time" (dc3ls-)
12/05/2017 at 12:11, STARS: 0
If I had to guess. Maybe it was an extensive mid cycle refresh?
"Smallbear wants a modern Syclone, local Maple Leafs spammer" (smallbear94)
12/05/2017 at 12:13, STARS: 0
Stolen from silveradosierra.com:
GMT or GM Truck Platform is the platform designation the trucks are built on.
The GMT800 is also known as NBS or New Body style. They were made from 1999 until 2007.5. GMT900 were made from 2007.5 until 2013 and also known as NNBS or New New Body Style.
OBS (Original Body Style) or GMT400-GMT480 were the first of the new model like after the GM C/K series. These trucks were made between 1988 and 2000. With the GMT480 being the 2500 and 3500 trucks.
GM did overlap for about a year between the GMT400 and GMT800 models. The slanty headlights are not the generational change. Just a mid generation front end redesign. This happens on most GM truck platform vehicles part way through a model line. The GMT800 is a good example. As the Silverado got the front end redesign for 2003. While Sierra did not get the different headlights in the GMT800 generation I do not think. Those slanted headlights are often refereed to as cats eye Silverado’s. Easiest way to tell a GMT800 from a GMT900 is the overall shape.
"Urambo Tauro" (urambotauro)
12/05/2017 at 12:17, STARS: 0
It’d be odd to rename the platform for that. But then again, some of these numbers separate GMC from Chevy, which I also wouldn’t expect to have different platform designations.
"Pickup_man" (zekeh)
12/05/2017 at 12:18, STARS: 0
Perhaps for the full size Blazer/2 door Tahoe?
Edit: After an extensive five minute research session, although I cant seem to find a straight answer my best guess is that the GMT 400 is for the 1500 trucks, and the GMT 480 is for the 2500/3500 trucks.
"duurtlang" (duurtlang)
12/05/2017 at 12:19, STARS: 1
Only 480 I’m familiar with:
"Steve is equipped with Electronic Fool Injection" (itsalwayssteve)
12/05/2017 at 12:20, STARS: 0
I googled GMT-480 and didn’t find anything. Could it have been those low-bumper heavy-duty work trucks?
"Urambo Tauro" (urambotauro)
12/05/2017 at 12:21, STARS: 0
Whoa, nice find! So that means my C2500 is actually a GMT480, though I’ve always thought of it as a 400.
I can’t help but be a little skeptical, though. As I understand it, C/K2500 trucks were just glorified 1500s with beefier suspension components (hence the nickname “heavy half-ton”), whereas the 3500s had a more substantial frame, which would be a good reason to set those apart as a separate platform.
"Urambo Tauro" (urambotauro)
12/05/2017 at 12:24, STARS: 0
Maybe...
"Urambo Tauro" (urambotauro)
12/05/2017 at 12:25, STARS: 0
(Blazer and Tahoe were GMT415 and 420, respectively.)
Re: 2500/3500- see my reply to Smallbear.
"Pickup_man" (zekeh)
12/05/2017 at 12:28, STARS: 1
Yep, saw that after I posted.
"If only EssExTee could be so grossly incandescent" (essextee)
12/05/2017 at 12:28, STARS: 2
This forum answer says the 480 was for the 2500/3500 trucks. http://www.silveradosierra.com/transmission/when-did-auto-4wd-become-a-thing-t642561.html
"Urambo Tauro" (urambotauro)
12/05/2017 at 12:32, STARS: 0
Ah, thanks for that link. I didn’t realize that the info Smallbear found came from a forum post. Something to be taken with a grain of salt, I suppose.
"Smallbear wants a modern Syclone, local Maple Leafs spammer" (smallbear94)
12/05/2017 at 12:36, STARS: 0
Maybe 400 was the general designation and never actually applied to any specific model? Your link mentions 450, 455 and 480... could those be 1500, 2500 and 3500? If the 2500 was only slightly different from the 1500 it would make sense for those numbers to be close.
One way or another my guess is that one of those designations is some type of weird sub-heading.
"cmill189 - sans Volvo" (cmill189)
12/05/2017 at 13:04, STARS: 1
I as understand it, heavy halfs are an actual 1500 with some 2500 parts. GM would put semi floater 14-bolt rear axles with 6-lug hubs under a 1500. The 2500s, whether same frame or not got 8 lug hubs. I’m not sure if a full floater 14-bolt was an option for 2500s. I’m curious about the frame though. You could only get a 2500 with an 8 foot bed. Seems like if they were using 1500 frames, you could get a 6 footer.
GMT800s got some other weird stuff with the 1500HD and 2500nonHD. Those were both 8 lug hubs with semi floating 14 bolts. The 2500HD got the real deal.
They did some other weird shit with “heavy halfs” way back when and you could get a 454 in a 1/2 ton. It would have 3/4 coils and leaf pack but still have 5-lug hubs and a 12 bolt rear.
"Urambo Tauro" (urambotauro)
12/05/2017 at 13:15, STARS: 1
My C2500 is a ’95, and has 6-lug wheels as opposed to the 1500’s 5-lug.
Yeah, when I hear about “platforms”, the frame is the first thing that I tend to focus on. That’s why it’s so weird to see different numbers between Chevy and GMC. I mean c’mon, what’s the difference between Chevy and GMC Suburbans to warrant a separate “platform” number anyway? You’d think that if anything, you’d use separate numbers to distinguish 4WD from 2WD versions.
"Urambo Tauro" (urambotauro)
12/05/2017 at 13:18, STARS: 1
Maybe 400 was the general designation and never actually applied to any specific model?
That’s not a bad theory. It’s possible that these other numbers don’t actually indicate crucial mechanical variations in the platform, but relate more to the overall finished product instead (like the GMT410/425 Suburban twins).
Part of me clings to the idea of a basic pickup truck as the “original” GMT 400, and the structure of the (incomplete) list makes me wonder if we’re missing a 405 in there. I think it would be tidy if GMT405 turned out to be the GMC version of the 400.
"cmill189 - sans Volvo" (cmill189)
12/05/2017 at 13:34, STARS: 0
You’ve got something that adds to the weirdness! I bet those front hubs are specific to light duty 3/4s and only 2wd. I forgot all the 2wd 1500s were still 5-lug at that point.
I feel like what you’re discussing is the truck example of what was wrong with GM back then. Seemingly endless options for essentially the same thing that led them into the ground. Should we be 12,000 options for about 10 different trucks? Sure. Should we build a Chevrolet, Pontiac, Buick, Oldsmobile, and sometimes a Cadillac of the same car? Sure.
"If only EssExTee could be so grossly incandescent" (essextee)
12/05/2017 at 14:24, STARS: 0
The 2500 and 3500 models apparently had a modified frame from the 1500, so they got a different chassis designation.
"Akio Ohtori - RIP Oppo" (akioohtori)
12/05/2017 at 15:33, STARS: 1
Info I’d found seems to indicate the 480 is for the Sierra, but all of the pictures show heavy trucks, so I’m inclined to think EssExTee is correct. I have the GMT400 C/K factory service manuals at home. If I remember tonight I’ll see if they have anything to say about it.