Now, GM put some damn fine engines in these trucks so there's very little worries there. In fact, if one of those friendly Jeep wheelers, or one of those great Toyota guys want to throw a bigger engine in their rig without a lot of expense, it's going to be a small block Chevy most of the time, or at least a 4.3 V6. They probably have parts for your small block at the grocery store. Well not really, but you can get cheap t shirts there eh?

Moving to the back of the rig, your rear axle could be a bit small if you started with half ton, but throwing a 14bolt in the rear of any full size GM truck is entry level mechanics and pocket change finance. A Detroit is cheap and that low hanging lip is a cutting wheel away from being a non point. We're good to go here!

Then there's the transfer case department, not much to worry about here. Most cases are pretty tough (can you say NP205?) and those that are a little less so have a lower low range, to get your rig going as slow as it can go. A combo of 700R4 and NP241 is a low buck way to crawl, but that's another story.

Finally, everything else that's bolted onto your personal monument to wheeling is fairly user friendly and cheap. So, disregarding that 10 bolt front you keep blowing up on "a simple baby step obstacle, really" with tires that "aren't that big, thirty eight inches isn't big", you probably just need to keep an eye on that gearbox underneath your feet. That magical contraption that translates the harsh rising and falling argument of the engine into a sensible and smooth explanation of momentum. Hmm, wordy aren't I?

Anyway, I'm going to lay down a list of transmissions that GM threw in their trucks from the general time of 1969 to 1991. I may miss a few of those obscure ones, or I may not have all the info on an individual unit, and I apologize for that. But, I know you just love me too much for anger, so, one two three go!

A TYPE / M TYPE

AUTOMATIC (TRANSMISSIONS) FOR THE PEOPLE

The automatic used in straight axle trucks are mostly of three types. The TH350 and TH400 three speeds and the super controversial 700R4 (early 4L60E)

My personal experiences with automatics is pretty straightforward. I started with a swapped in 700R4 and ran it fine for a year or so. It didn't like light wheeling though and decided to leak quite a bit. Boo to that! I dragged the truck to a transmission shop and the owner, an avid wheeler himself, helped me find a TH400/NP205 combo and put it in. I wouldn't go back. 

Anyway here's a rundown of details.