Re: drivetrain help
Hrmahhh... yeah, I'll try and help. There's a lot of room to interject opinion here, but I'll try and stay unbiased.
First, all GM cases up to 87/91 dropped passenger side
Belts? Maybe chains, I have never heard of a belt drive t case on anything
With a 1982 I'd bet 99% it's a NP208
Now here's my thoughts -
If you don't plan on getting super large tires and beating the [bleep] out of your truck, I'd keep the 208. If you stay 37" tire and under and donít plan on swapping axles in and out, it should be fine.
The TH400/NP205 combo is very strong, but it has a 2.0 low range and the tranny is rumored to suck a lot of power compared to other autos
A TH350/NP205 combo would be good too, but an NP205 is heavy and again only has 2.0 low. On the plus side, it does have a fixed yoke if not made in 1980 and is beefy
The TH350/NP208 combo you have now is strong enough for what I think you're going to use it for and has a lower low range at 2.61, but it does have some drawbacks. The 208 is aluminum and hangs lower. It usually has a slip yoke, which isn't all that desirable for quite a few reasons, driveshaft balancing and fitment and the ability to take the rear shaft off without puking all the fluid out come to mind.
So you have various options here. A TH400 would be beefy, but a TH350 isn't going to rollover and die like a 700R4. Also, TH400 are more expensive and getting harder to find, but just about the same price to rebuild as a TH350. A TH350 rebuild or rebuilt tranny is VERY cheap compared to a 700R rebuild with the right parts.
NP208's may not be the ultimate in durability and the slip yoke is kind of annoying, but you can get a SYE (slip yoke eliminator) kit to remedy that. Plus, you get a lower low range, a lighter case, and replacement cases are dirt cheap. I have one in my shop I'd sell for $100 or so. It does hang down a bit lower though, and that can be a consideration if you ever want to be running drivetrain bashing trails.
An NP205 is, as I've said, a rocksolid case, but heavy and lacks a decent low range. It is also slightly harder to find these days.
I never mentioned an NP203. It's a full time case and not really a good swap option. I have one in my K5 and like it fine, but I'd never wanna put a standalone NP203 into anything I had options with. If I have one in the truck though, it's fine with me.
So in summation, I say go get your tranny rebuilt or find a new one. I've heard of great rebuilds for $400 - $600. The TH350 is a damn good transmission and swapped into many vehicles around the off road world. It also can stand up to some abuse in the big ass trucks we tend to build.
Your other option is shopping around for a matched set (Tranny/Case) or putting a new case behind your TH350. Any swapping of cases you do is going to need an adapter. They are expensive. I know.
I had a situation kind of like yours a while ago, blew up a 700R4/NP208 combo (well just the tranny). I was going to put a rebuilt TH350 in front of the np208, and kind of regret not doing that to this day, but the tranny guy, who was an off road dude, sold me a TH400/NP205 combo out of his parts truck, and installed in with a quick inspection. I love the combo, and the low range is good enough, but the tranny is nasty looking and has a leak, and I think I may just have to have it gone through soon. I think there's a shop relatively near here who will go through it for $400 and guarantee their work for a while.
Hope this helps
Shane Wager / Resurrection Joe