When I first bought the D2 it had a shimmy/rumble from the rear end at 65+ not shaking your fillings out, but not right, the shimmy/rumble changed with the road surface and not with loading on the drive train and the rear end did have AT tyres fitted so I swapped these out for road bais tyres and the problem was 80% better but still there
so next step I thought better check the prop the rubber doughnut is in very good order so unbolted the uj from the brake drum and spotted the problem who ever last had the drum of hadnt tightened the countersunk bolt up and it was sitting proud by about 10thou. so the uj wasnt sitting square uj is fine refitted everything and now I have a vibration free drivetrain. just goes to show something so simple can cause problems the PO thought it had knackered prop

Thanks for posting that.
It just goes to show again that transmission vibration needs a very careful check of all the parts.

One little screw not fully wound in, I can imagine a garage would charge a lot of money to repair the drive train