I had a multiple problems with mine. wrong washer holding the universal joint tight to the ****** tailshaft. It caused the bolt to loosen up and the U-joint would smash against the bearing retainer.
Worn c-clips in the ******.
Oil on the clutch.
Clutch chatter could be the culprit for sure. When in reverse, the rear axle is pulling on the drive line instead of pushing. This puts things in the opposite bind that they're in normally in forward gears. Loose mounts can cause problems in both forward and reverse but may be masked by adjustments to take up the slack. There could also be something going on with the reverse idler gear but that would be an uncommon thing.