alk1174 wrote: I hear it can be hard to squeeze a driveshaft in next to the trans pan with narrow toy axles.
I don't know why? TH350 and TH700R4 pans are almost identical. The TH200-4R transmission was never available in 4wd, so I don't know what kind of issues you'll have coupling it to a t-case. It's lighter duty than a 700R4, but if you kept it cool, bought a good transmission reprogramming kit (Not the B&M bull) like Trans-Go, and changed the fluid like you're supposed to in a performance automatic I don't see why it wouldn't last.
Personally, I'd just run a TH350 in it. They're shorter than either the 200-4R or the 700R4 due to having one less clutch/sprag/planetary setup, are entirely clutch shifted with the band used for hold back (IE stronger/faster shifts) and much higher parts availability. With a 4.3L and a light rig like a sammy, I think somewhere in the neighborhood of 1200-1500 stall would be good to make it snappy and responsive.
Matt and I have talked about using a trans-brake on the trail to get the clutch like releases when you need to bump it. There is ALOT to know about using a trans-brake, but with stock motors and good quality torqueconverters, I think it's feasible without much risk.
I have many more thoughts on the GM automatic transmissions...