1985 K2500 Build/LS Swap

Long time stalker first time poster here on the squarebody forum.

A little about myself, I have been playing and wrenching on cars majority of my life but have limited myself to mainly hot rods. Just "finished" up my 79 el camino project and started racing it in autocross this year. 383 stroker, fully worked over suspension including coil overs on all four corners. It has been a blast to build and now race. But with my wife and I having our first child a few years back driving around as a family is impossible in the el camino. So after two years of searching I finally found this burb hiding away. It is a 1985 GMC K2500 with the 6.2L diesel backed by a 700r4 and 208 transfer case.

Photos of el camino, can post up more if


Once I got it home I fixed up the leaking injectors and got it running to just see how many little things will need to be repaired and in what order.

First bath



Quickly restored the single stage paint, roof needs some rust repair so I left that polishing till later:



Right now I am laying out the plan for an LS swap along with a new trans. Will post up my plan later as I want anyone and everyone to poke holes in it before I get started.

Brief update:

Scored an 04 Sierra 2wd with 120k. Yanked the motor and trans and sent the body off to the scrapper

Cleaned up and painted the engine and trans. Still deciding on painting the valve covers to match or not.

Got pretty lucky and only had two exhaust bolts snap in half. Also took a look at the wiring and decided I will for sure go with a stand alone harness

Listed up the 6.2 and trans for sale. Quickly ditched the 6.2 and working on the final sale of the trans.



Next update will be on a final clean up and reassembly of the engine. Tearing down and swapping output shafts and tail housings. Scrub down and repaint of engine bay and underbody.

Engine bay cleaned up mostly and painted, beyond over cleaning an old diesel truck from 1985, on the plus side zero rust!


Took a stab at tearing into the 4l60e to swap out the output shaft. No guarantees that it works but turning the input shaft makes the output shaft turn when it is in drive!

Moving quick!

CountKrunk said:

Moving quick!

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Shoooot between work and raising my toddler I am limited to a few hours a week. Much slower than some of my previous builds but I appreciate it! Next week I am taking the week off to stay home with the kiddo so hoping to make a decent amount of progress everyday during nap time

Looking good! Love the Elco, I've got a soft spot for G-bodies. You're gonna love the LS swap, it makes driving these soooo much more enjoyable

TotalyHucked said:

Looking good! Love the Elco, I've got a soft spot for G-bodies.

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Me to when I can find'em

Made some progress over the past few weeks. Dropped the motor and transmission in, don’t be a bone head like me and mount it far as possible forward. Once I had a few people on here chime in we remounted the motor and the transfer case sits right back in the factory location.

Was able to source some speed engineering headers, nobody will ship them to California.

Decided on a spectra cu730 radiator. First one from rockauto came in warped beyond belief and even with me sitting on it the thing would not budge!
Thankfully the second one they sent is perfect and is also a perfect fit!

Since this had hydro boost with the diesel I plan on keeping that. And my goal is still to keep as much factory suburban parts or factory Silverado donor truck parts so we can repair it on the road. Took the Silverado factory pressure hard line and tweaked it to meet up with the suburban soft line.

Painted up fender wells and core support.

Nasty-LSX said:

Me to when I can find'em

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Thank you both! What’s nice is the aftermarket support continues to grow every year on the gbodies. As you all know a hot rod is never done but for now the el Camino is a driver and race car that only needs maintenance.

I don’t have any photos right now but I was able to retain 90% of the factory suburban exhaust for now. I know it’s only 2.25 to the mufflers but without any restrictions in the exhaust that should be good enough with true duals. Next up is finishing the wiring, running fuel lines (waiting on hot rod fuel hose), fluids and then firing it up.

Also could use recommendations for who you guys have used to remove the vats and emissions from the ecu. Considering going with Blackbear tunes.

Blackbear usually gets good marks (no personal experience), but if you're up for a small challenge to learn a new tool, picking up an HPTuners setup is probably a good option. Easy to fix those issues, and it is a great diagnostic tool if nothing else. It should just be 2 credits for you, and there's plenty of files to copy/paste from to get the right codes deleted.

The other option I have used is LT1Swap, Brendan there is quick and good, he's been doing that service for years. It won't be a performance gain generally, but for a stock engine that just needs the toggles switched, and things like rear gear/tire size corrections, it's probably the easiest way to go.