It was a bad centre bearing, a mechanic has put a new one in completely ripped me off $350 later.
Now when it drives hitting bumps you hear a knock under the car as if the tail shaft is knocking up against something.
Do you think maybe he hasn't balanced the shaft at all? near the joints?
I wouldn't be complaining too loud....It cost me $604 to get the tailshaft rebuilt for my VC
I had the centre bearing, CV, unis, 1 uni joint piece, and rebalanced....Originally I was quoted $550 but that blew out big time
Just for reference...The tailshaft has a centre bearing and a C.V....The C.V is actually the piece that has 6 allen key bolts holding the whole tailshaft together and does cause vibrations when it starts to clap out..
Only reason I mention this is, I ordered a centre bearing and when I collected it, it wasn't the piece I was after.....So this might help others in the future...
Here's a picture of the centre bearing and C.V...