Square Body Suburban Info

[NatersXJ6]

What years count as GMT 400? I have a 99 behind my garage right now and can take a few measurements for you. Based on the mechanical condition of it and the work I’ve been doing, I think the systems aren’t all that well designed, but you get what comes with the Chevy logo, and I only paid $500 for this truck.

 

[jonathon]

If I go the burb route, then I will deffenitly get barn doors. My parents had one of these growing up. I do remember how heavy that thing was. I thought about the GMT400 but I really have no experience with IFS suspensions and pricing a solid axle swap, I was at 4k without the axle.

IFS isn’t terrible and in someways very easy to work on depending on the year. New ball joints, TRE’s, idler arm, and pitman arm go a long way towards making it drive nice. Keep the torsion bar crank to no more than 1.5-2” and tires no bigger than 33” and it’ll do okay. Avoid bracket lifts, all show and no go.

I got lucky with my truck. Since it’s a 1988 it has bolt in lower ball joints. Replacing all 4 only took 3 hours with hand tools. Last square body 10 bolt I did took all damn day since nothing came apart easy. No salt here.

I’ve thought about trying to find another square body burb. Still lots of clean ones around here for cheap and for me I’d probably put a crate L31 in it with a Holley Sniper and a TH400 backed with an NP241. Dirt simple setup and common to find. LS swap is another good option, but its hard to ignore that a brand new GM L31 can be bad for $2k.

 

[nitro_rat]

IFS isn’t terrible and in someways very easy to work on depending on the year. New ball joints, TRE’s, idler arm, and pitman arm go a long way towards making it drive nice. Keep the torsion bar crank to no more than 1.5-2” and tires no bigger than 33” and it’ll do okay. Avoid bracket lifts, all show and no go.

I got lucky with my truck. Since it’s a 1988 it has bolt in lower ball joints. Replacing all 4 only took 3 hours with hand tools. Last square body 10 bolt I did took all damn day since nothing came apart easy. No salt here.

I’ve thought about trying to find another square body burb. Still lots of clean ones around here for cheap and for me I’d probably put a crate L31 in it with a Holley Sniper and a TH400 backed with an NP241. Dirt simple setup and common to find. LS swap is another good option, but its hard to ignore that a brand new GM L31 can be bad for $2k.

x2 on a front end rebuild to tighten up the IFS trucks! With practice, ball joints and all outer work really on the dana 44/corp 10 bolt front isn't bad. I just use a hammer instead of a ball joint press. Crossover is as easy as a $269 ried racing knuckle for the right side. Easier than adding the arm to an old dana 60 knuckle...

What years count as GMT 400? I have a 99 behind my garage right now and can take a few measurements for you. Based on the mechanical condition of it and the work I’ve been doing, I think the systems aren’t all that well designed, but you get what comes with the Chevy logo, and I only paid $500 for this truck.

GMT 400 ran from 1988 to around 2000 with some overlap. In 1988 the squarebodys became "R and V" instead of "C and K" (denoting 2wd or 4wd). The squarebody continued alongside the GMT 400 as Suburban, Blazer, and select one ton truck applications until 1991. GMT 400 Suburbans ran from 1992 until 1999. GMT 400's continued alongside the GMT 800 ("NBS" in internet forum slang) from 1999 until maybe 2001 in select applications. In 1999 either body style truck was available. The GMT 400 Escalade and GMC Denali continued until 2000. I think there were some select one ton applications available as GMT 400 in 2001 (think cab/chassis).

 

[NatersXJ6]

Yes, I have a 99 GMT 400 burb. Happy to grab a few measurements if you want me to this weekend. Pretty busy until then.

 

[zoomad75]

There's a chart for the speedometer gears just like there's a chart for the DRAC module pin outs. Real simple as long as you only need to change the driven gear. Not much more complicated if you need to swap the drive gear too. If you're like me and have owned/driven/parted out these trucks for years you just go get the right color gear out of the pile...

You'll likely see a gain in economy going to a lower (higher numerically) gear in your 5.3 K5. If you keep the RPM's at or just below 2000 when cruising on the highway (probably just below 70 mph) you will probably do ok. Even better if you drive 65!

I had given the idea of deeper gears a thought. It would keep the engine more in its torque curve. But then an 8.1 kinda fell in my lap and I horse traded for an nv4500 5-speed trans. So brute force for the solution.

Kind of why I threw this platform into the mix. Sheet metal seems to be dirt cheap on LMC compared to classic car metal, 350's are plentiful and I have 3 of them currently in my fleet, so the cross-compatibility of some parts would be nice.

Weird question does anyone know the dimensions of the rear cargo area without the third-row seat? I will not have access to actually check one out for a few months so doing my comparing and contrasting via numbers and feedback as of now.

Sheet metal from LMC is cheap and falls under the get what you pay for idea. There are other sources for better sheet metal, but it runs a bit more.

I don't know the dimensions, but with the 3rd row out and the middle seat down a Burb will swallow a 4x8 sheet of plywood without a problem. 3rd row seat in, space is comparable to the space between the rear seat and a gate on a K5 Blazer.

 

[nitro_rat]

Sheet metal from LMC is cheap and falls under the get what you pay for idea. There are other sources for better sheet metal, but it runs a bit more.

Aftermarket sheet metal for these is junk. It's thinner than stock, the hoods kink in the middle and show fingerprint marks from shutting them normally. A friend of mine restored a very nice '74 Chevy C20 a few years ago. It had minor rust in the bottoms of the fenders and doors. He went with all aftermarket metal against my advice. Complete front clip, doors, and bed. The thing looked nice from a distance but there was nothing you could do to get the panel gaps right and the doors leaked water in the rain because they aren't the right shape. Truck was nice enough I would have left it alone. He was sick after all the work and sold it for a considerable loss...