When mine goes, I'll put in an R151. Very similar to your R150, but with a lower 1st gear, as it was intended for use with the 22RTE motors.

As far as T-cases go, the gear drive ones are the way to go, for the reason you mentioned: lots of gear and dual case options. Stay with, or upgrade to, 23 spline shafts and you'll be fine. If you're seriously running 33's, you won't break the t-case. If you start running 39's, you might want to cryo the t-case output shaft. See Marlin's site for tranny and t-case options, and Bobby Long's for cryo'd shafts.

BTW, Bill (Red Chilli) is running a 3.4, R151 and dual gear-driven cases. He lives close to me, and I've not heard it blow... <img src="/forums/images/graemlins/smile.gif" alt="" />

Mark