You can replace the universal joint itself ... in one of the photo's, you can see the circlip that retains the bearing cap (there are 4 caps ... 2 on the piece that bolts to the diff and 2 on the tail-shaft itself).
If there was a weight that balanced to tail-shaft and it has disappeared, then you need to get the tail-shaft re-balanced
Google found me an example on first search:
https://www.google.com.au/search?q=r...seMPvey6mAs_23