It is hard to say. What make of Drive Shaft Support did you use? I settled on one by Myele even thought there are no longer great supplier of Parts. There is 2 companies that sell the Support with the Bearing already in it and People have said they do not last.
This is a fairly recent threads:
Sticking U-joint causes Vibration that Rips up several Drive Shaft Supports turns out to be Rusty Needle Bearings
W123 Propeller shaft vibration tears up rubber mounts, replaced nearly everything