You could have one of 3 problems,
1. The U-joint is bad on the T-case end.
2. The Yoke (Output Bearing) of the T-case is bad.
3. Slip Splines are bad on the Propeller Shaft (drive shaft) (which I don't think is the problem).
You need to figure out which one the issue is, if it's only a U-joint then no issue, if it's the bearing then that would be a PITA.
Now if for some ungodly reason it's beyond repair, I would go to a junk yard and get a new one, install a new U-joint on each side and call it a day for around $80.