1990 GMC Solid Axle swap truck

[Twin Turbo Skylark]

This is my daily driver, 05 GMC 1500 and I just got a new project truck a 1990 GMC 1500 also black.

Before:



With 6.5" BDS lift and 35" tall 12" wide BFG AT:











This 1990 gmc came with independent suspension but for real off road abuse you want some solid axles... Tons of work went into this and it's really well done.



Pulled it up onto the flat deck for safe keeping, love that PTO winch:







I got the truck as a roller, no engine or trans but I have these 2 trucks to choose from for donors. the 01 GMC 2500 or the 1988 Chevy with 5 speed manual and TBI 350. Obviously the TBI would be an easier swap but the 6.0 would be much better.

[obijuan]

6.0 nv4500. No brainer for me.

[andrewmp6]

What axles are in that truck ?

[BILT4ME]

Something has been changed. That 90 has leaf springs on the front. That version had torsion bar front suspension.........

[obijuan]

Those axles are a 14bff and a dana 44

[Twin Turbo Skylark]

Yes it has had extensive modifications to fit 14 bolt rear end and Dana 44 axle in front. The tortuon bar suspension was removed in favour of a Dana 44. The wheels are 8 lug and those pizza cutter tires will be replaced with much taller and wider mud tires.

[special-K]

Nice roll cage. Pizza cutters are tall and skinny. Those tires look like typical standard profile. Pizza cutters would be a good choice since the track width of the swapped-in axle is so much wider than stock

[andrewmp6]

Depends the tire size you want,Past a 37 that dana 44 won't be happy anymore.

[Twin Turbo Skylark]

Good points, yes these are normal sized rims and tires, not really pizza cutters. I would not go with anything taller than a 35 I really like 33s actually. Much easier on parts and better fuel mileage. I think a set of 33x12 like had on my 81 would be perfect and good point I do not need a deep dish wheel as the wheels that are on it now put the tires just about right with the fender flares. I do like to have the tires inside the flares as it keeps the cops off your butt.

This is the 81 that I sold, showing the 33x12 BFG MT that would be what I would use. Just more backspacing on the rims so they don't stick out. The deep dish rims also reduce the clearance in the wheel wells on the front so thats another reason to avoid them:



Speaking of which I swapped the 35s on my daily driver out for 33s and it looks better, gets better mileage and the ride is smoother:

[b454rat]

FYI track width between IFS and solid axle is the same, it's the offset of the rims that make it look wider. Who's kit is the SAS from? posted in the other tread, you need to fix the steering!!!!

[dieseldawg142]

if it was me, i'd drop the tbi 350 5-spd in it. it is a great little combo in a stepper.
besides dropping in with no issues, the 350 can be a decent motor. i have a '90 gm stepper as well(with ifs, and it is not all bad, it wheels almost as good as my K30) with a tbi 350 5-spd & 3:73's, locked in low it's like a mountain goat- put your foot to the floor & it might make 10 mph tops...
it's my daily so mods are minimal, has to get me to work. chipped, cammed, 3" exhaust, it will light the 33's in 1st, and i can even get a chirp in 3rd, yet with the 5 spd, can still pull down mid teens or so with fuel mileage
i see when it's on the flatdeck, no rollbar, looks much better without i think...

[Twin Turbo Skylark]

Originally Posted by dieseldawg142

if it was me, i'd drop the tbi 350 5-spd in it. it is a great little combo in a stepper.
besides dropping in with no issues, the 350 can be a decent motor. i have a '90 gm stepper as well(with ifs, and it is not all bad, it wheels almost as good as my K30) with a tbi 350 5-spd & 3:73's, locked in low it's like a mountain goat- put your foot to the floor & it might make 10 mph tops...
it's my daily so mods are minimal, has to get me to work. chipped, cammed, 3" exhaust, it will light the 33's in 1st, and i can even get a chirp in 3rd, yet with the 5 spd, can still pull down mid teens or so with fuel mileage
i see when it's on the flatdeck, no rollbar, looks much better without i think...

Thanks for the input I don't think the truck is too heavy. I think it looks clean without the roll bar too. Do you have pics of your truck? I love the look of the steppers.

Originally Posted by b454rat

FYI track width between IFS and solid axle is the same, it's the offset of the rims that make it look wider. Who's kit is the SAS from? posted in the other tread, you need to fix the steering!!!!

Thanks for noticing that I will look into options for fixing the steering. I have no idea what kit the Solid axle swap is I got the truck like this for $500. Well worth the $ to me.

[special-K]

Originally Posted by b454rat

FYI track width between IFS and solid axle is the same, it's the offset of the rims that make it look wider. Who's kit is the SAS from? posted in the other tread, you need to fix the steering!!!!

The body tapers in, is what the issue is. Tracks may be the same, I never checked, but the body is narrower than a square body and that puts the same tire on the same wheel out farther in relation to the body. My experience is with 8-lug IFS and just 8' wheels with 285/75s put the tires out past the fender flares. Do 8-lug trucks have that much less backspace than 1500s? I always assumed they had a wider track than a 1500s, hence the need for fender flares. 2wd 8-lugs run the same wheel and don't use flares. I had to replace my fenders with non-flare 2wd fenders and use Bushwacker Extend-A-Fender flares to get a little more tire coverage for 285/75-16s on 8" AR23s (and Weld Outbacks).

[Twin Turbo Skylark]

Very interesting guys. Being a customized truck we can just keep changing things till we are happy. Not like I need to worry about keeping anything original Lol! I think those rims could stay if I added some 33x11 tires... 12 inch tires may be a bit wide for them. It's nice that it has a suspension lift but no body lift it looks good.

[special-K]

That sounds about like a 285/75-16. Here is the '95 K3500 I swapped fenders on to use Bushwacker Extend-A-Fenders for reference. There wasn't much I didn't change on that truck. And those are Super Swamper SSRs. Tires like BFG A/Ts will bemore forgiving on tread width


I keep thinking I'd like to swap a solid axle (Dana44 or 10-bolt) with stock springs under my '95 K2500 Suburban and use this size tire...or 255/85-16 pizza cutters. I want it to look like it would from factory if they used solid axle still, but with oversized tires.

[dieseldawg142]

Originally Posted by Twin Turbo Skylark

Thanks for the input I don't think the truck is too heavy. I think it looks clean without the roll bar too. Do you have pics of your truck? I love the look of the steppers.

steppers are fairly light, think mine weighs just over 4500 lbs
285/70R16 on 8" eagles (approx 33x11.5 x16)
cranked the bars 2 inches & put some add a leafs in back, no sheet metal contact anywhere, even when all twisted up

[Twin Turbo Skylark]

Originally Posted by dieseldawg142

steppers are fairly light, think mine weighs just over 4500 lbs
285/70R16 on 8" eagles (approx 33x11.5 x16)
cranked the bars 2 inches & put some add a leafs in back, no sheet metal contact anywhere, even when all twisted up
Attachment 1599324Attachment 1599325

Thanks for the pics... I am jealous of your location I grew up on Vancouver Island but live in Edmonton now...

[SuperBuickGuy]

The net is such a small place.... I like either of your plans for the 90, but what are you going to do for a transfer case? both of the later chevy trucks are driver's side drop t-cases.... there isn't really a 'cheap' passenger side, part-time 4x4 case that directly swaps to the NV4500 transmission. Of course, you could call it an opportunity to put a black-box in or similar....

love your black truck, I sold its twin to a Canadian a year ago - miss it, sort of, but don't miss the solid-axle ride.

[Twin Turbo Skylark]

Oh wow nice to see you here too! tha me for the heads up about the transfer case. The truck came with two transfer case but I'm not sure what they are I need to check them out...

[SuperBuickGuy]

In many ways it'd be better and cheaper to buy a Ford front axle (drive's side drop). The benefits are:
1) you can get a High Pinion Dana 44 - which is stronger then a low-pinion dana 60
2) they're plentiful
3) the 90 transfer case can be modified to be part time so in the end you'd have less work - simple weld new pads on
4) most Ford axle are cross-steer - which is a good modification for GM axles because it greatly reduces bump-steer.... on top of that, your GM box will work with the Ford Axle

Also, you can find a lot more driver's side drop dana 60s. To convert couldn't be simpler - use the knuckles you have on the Ford axles (Ford are 5 or 8 lug).

oh and best of all, one more Ford is removed from the road

[Twin Turbo Skylark]

Lol thanks!

[b454rat]

Almost any GM case will bolt up to the trans, just need to get splines right. Best and easiest is to find a 91, possibly a 90, I haven't been able to fine out, Blazer or burb. They have the pass drop 241 with VSS. I'm not sure, but I think all GM 5-speeds use 32 spline output, but it's an easy swap. Down side is it's tough to find a 91 only burb or blaze. I know where there is one, and only every seen barely a handful. Also, these cases are part time already, no mods to make it one. The axle you want is from a 78/79 3/4 ton Ford. They already have flat tops knuckles, and will pretty much bolt in, just need to change shock mounts. You can use a 77 and older 1/2, but they require more work. Not in less your going crazy, prolly won't need a 60. They are getting insane on pricing anymore. I'm seeing the 80s/90s version going for over a grand....

[SuperBuickGuy]

b454 has a good point, the reason you want the 77-79 3/4 ton is wall thickness... though I'm not sure about bolt in since they used coil over and arm not leaf spring.
this is the axle he's talking about (it's upside down at this point)


wall thickness


I swapped sides for my FJ40 - so it's a high-pinion, passenger drop dana 44 from a 77 Ford f250. I used the ford outers but then dana 60 stub shafts (and nitro gear axles). I spent a lot on the axles, but I wanted the clearance of the dana 44. That said, functionally this is stronger then a stock dana 60. It has 35 spline axles.

assembled

[b454rat]

I mentioned 78/79 3/4 ton cause they are leave spring, not coils. You can use 77-older 1/2 ton with coils, they have welded on Cs, so grind em off and weld on spring perches. Do not use 78/79 1/2 ton with coils, as there is no tube where the Cs are, they are "molded" into the tube. 77-older 3/4 ton is low pinion, it would work but driveshaft angle would be steep with a lifted truck such as OP has.

[SuperBuickGuy]

Originally Posted by b454rat

I mentioned 78/79 3/4 ton cause they are leave spring, not coils. You can use 77-older 1/2 ton with coils, they have welded on Cs, so grind em off and weld on spring perches. Do not use 78/79 1/2 ton with coils, as there is no tube where the Cs are, they are "molded" into the tube. 77-older 3/4 ton is low pinion, it would work but driveshaft angle would be steep with a lifted truck such as OP has.

So you're saying this differential



doesn't exist and it's merely a figment of my imagination under my imaginary FJ40? That's a pretty bold statement.