Eli McCrae

My 92 K1500 4X4 (5.7, auto, 3:73 ratio) is getting a transplant.
I purchased a Goodwrench crate 350, for 69-85 models (Emission isn't a problem here).
My 700R4 is wasted, and by comparing all the available GM trannies, I'm looking to swap a 4L80/85 in there.
I like the gear ratio spread.
Also going to swap differentials using a lower gear (4:56 or 4:88).
I don't do mud, just snow and ice, and moving things, hauling, etc.
Basically a streetable work truck/ winter survivor.

I'm carbing this one, using Vortec heads, Edelbrock performer manifold and Holley carb. And older style ('76 HEI distributor).
Not a fan of the gear drop of my 700R4 (3-1 First, 1.55 Second) I think the 4L80 being more like a TH400 with OD will fare better.
When I used to drive the truck in stock configuration, I irritated traffic with my doggy stock combo.
I'm sure running 285/75R16 tires didn't help my ratio any, but they got me to work when I'm sure the 265s that were replaced, would not have cut it (Indiana snow).
Always went to work early, before the plows were out

My main question is- how do I deal with the different sized output shaft of the 4L80, when going with my Transfer case (which I believe is NP241)...
Or, are there any issues swapping in the matching Transfer case from a 4L80-equipped truck?
Any other ideas/advice is welcomed...thanks

oilcanhenry

This matter is going to require some extensive study. Were I you I'd just sell the Chevy and get what you need, but most vehicles with axle gears lower then 4.10/4.11 are special ordered from the factory. Holley was always my favorite brand when carbs were standard issue. Easy to work on and took on steep hill-climbs without flooding out.
My K-1500 has the solid NP-241 manual transfer case and I wouldn't trade it for the automatic 4x4 transfer cases for anything Wish I could put locking hubs on but not possible these days.

burnhedge

The transfer case is going to be the easy part. Just swap in a 32 spline np241 or borg warner in, or the input from a 241.

Swapping to a transmission that's electronically controled is going to be the headache. Also your driveshafts are going to be the wrong lengths.

I swapped the 700r4/np241 in my 88 to a nv4500/np241. I prefer a manual anyway. Both are the same length and can use the same cross member. Nv4500 requires no wiring (maybe for back up lights). The swap took all of 5 hrs since I had the whole donor truck on site. Before I upgraded the axles I was running 33's with 3:42 gears and it wasn't bad at all with the nv4500. Now that I have 4:10 I can't remember the last time I used 1st gear.

Eli McCrae

I had considered the NV3500 or 4500 as well, I like manual trans better. However, after I move next year I'm gonna be in a large town and the traffic is bat**** crazy fast there...
My old setup was bad enough in a small town.

My main transportation is an underpowered four banger car (155hp), it is a real challenge to even pull out into traffic in that town. Foot to the floor, powershifting all the time.
That's why I want an Auto Trans.

I get tired of being the underpowered car in a field fit to run the Indy 500!!