I agree that it could be best to replace all the other bushings first and see how that improves things. At the base of the gear lever, and on the side of the bell housing. I didn't think I had so much play in those, but they were easy to replace and I was wrong. Slop in the gear linkage was 90% gone after replacing them. It works great now.
Just thinking- the U-joints really don't move a lot and are closed, so they shouldn't wear terribly.
Vince