Steve ..braking the driveshaft was on some of the very first vehicles.. Placing brakes there causes the brakes to stop ALL of the moving mass of the rear end! I remember driving a vehicle that had shaft brakes on it...it didn't stop worth a $hit!!
Copcentrate on the front brakes.. 80/85% of stopping power is in the FRONT! Some nice one ton disks and calipers would be what I'd be looking to madify...if I wanted to stop! Rear drums are enough to stop the back end. Rear disks don't help stopping any at all.
If I was going to build up a Jeep I think I'd be looking for a donor vehicle with the axles and brakes I needed and I'd be purchasing the whole thing.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />