A hole in the ujoint bellows or the exhaust bellows?
In the ujoint bellows, water intrusions quickly start wiping out gimble bearings, ujoints, ujoint seals, and then getting past the seals into the drive itself.
Assuming this has something to do with your loosing the flywheel housing, ujoints, etc. from your "How bad is it" thread, then yes. The input shaft seal in the upper gear box is not designed to keep water out, only gear lube in. What happens, is the seal washer in the drive gets rusty, cuts up the seal like sand paper, water gets into the bearings and gears, and water doesn't have near the lubrication characteristics of oil, and you end up with rusty bearings and gears. aka, a huge expensive mess if not fixed quickly.
