The Overlander: Gen3 LS, 6L90, MP1125 AND BODY SWAP

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Urbanburban22

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Joined
Apr 22, 2022
Posts
34
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Location
Colorado
First Name
David
Truck Year
1991
Truck Model
Suburban SLE V1500
Engine Size
5.7 TBI
Hey all! Making this thread to document the build, ask for advice, and answer questions for anyone who need help. So where to start?

This all started a few years ago (3ish) when I bought my 91 Square V1500 suburban. With a poorly done respray and a lot of little problems here and there the rust didn't seem bad and well I was happy to own a square eith barn doors. As time went on I modified the TBI and everything else. (intake and ported tbi unit, 454 injectors, exhaust, ignition including a 6AL box, overload shocks, bumpers. Wheels, tires, lights, and so on)

Got to a point where after spending a grand or so on the gutless 350 and rebuilding (fully built) the 700r4 where I just was not satisfied with the power, and the body was starting to get rough (almost 500,000 on the clock)

So I went to my local salvage yard and pulled a 5.3 lm7 gen3 LS. Truck Norris cam, valve train by BTR, forged rods from egal, icon pistons, ls7 lifters, and the block was bored out to a 5.7. Down the line a bit I got my hands on a 6L90 (ALL the Sonax upgrades: HD 4-5-6 clutch piston kit, billet 1-2 piston, unbrakable pump ring kit, pump pressure spring, 6l90/80 ZIP kit, billet base converter) I also just got my MP1125 (floor shift) transfer case in from LQK (73,*** miles used)

Then I started looking into the unfortunate rust problem in the back third of the truck BODY. I have another thread where all photos are posted. It's a little too far gone for this build.

In comes a trip to Cedar City Utah for a 1985 r1500 roller that's almost rust free (500 bucks!)
Then comes the body swap (currently underway, just have to install 3 patch panels on the 85 body first) so essentially I'm taking the 85 body and 91 front clip and setting it all on the 91 4wd frame with the new power train. The 91 body will go on the 2wd 85 frame and be my ratty mess around street suburban. All body mounts are in the SAME locations on both frames. I did cut the 4wd trans tunnel from the 91 and weld er into the 85 body, same with the 85 to 91.

At this point, I'm waiting for all the fancy expensive junk to come in from holley (hi ram I take, term. X max with 6l90 controller, drop in efi fuel pump, frost bite fans, and so on) and some seam sealer. After the body swap is finished utll get some new axles, custom drive shafts. It'll get a shot coat of primer until I can afford a paint job. There will be lots of long time consuming little things like the undercoat, interior build for the camper, wiring, crossover steering, just a LOT.


Here are some of the photos: not the current look of the engine, but only photo i have. There will be more photos as the build progresses, along with updated posts.
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Urbanburban22

Member
Joined
Apr 22, 2022
Posts
34
Reaction score
44
Location
Colorado
First Name
David
Truck Year
1991
Truck Model
Suburban SLE V1500
Engine Size
5.7 TBI
Build updates:
LS is finally in.
Body swap went without a problem.
Minor issues being different connectors for power locks, and some stuff on the steering column. Removed 90% of all the wiring. Only really left the HVAC and lighting alone.
Using most every part possible from the 91 body for the 85 body. Brake components included.
Biggest problem at the moment, is headder fitment. Drivers side long tube hits the stupid leaf spring shackle for the front springs.
So the next priority is axle swapping it. Will unfortunately have to do that after I get all the new weather stripping and a few other things from LMC.
I'm currently looking for tailgate glass, regulator, and motor. If you know someone selling please send them my way!

Enjoy the pics.
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Urbanburban22

Member
Joined
Apr 22, 2022
Posts
34
Reaction score
44
Location
Colorado
First Name
David
Truck Year
1991
Truck Model
Suburban SLE V1500
Engine Size
5.7 TBI
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CountKrunk

Full Access Member
Joined
Aug 3, 2023
Posts
450
Reaction score
1,053
Location
SW VA
First Name
Count
Truck Year
1984
Truck Model
C20 Custom Deluxe 3+3
Engine Size
v8 350
Going to be sick!
 

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