Hi mate just a thought check the propshaft yokes are alligned I.e ujs at either end are in line as in cups at 12 &6 , 3&9 if you get me came across this a few times when folk have had the shaft split at the sliding joint then put it back in a different position,wear on the ujs or sliding joint can throw the balance. Pj props in hillington balance shafts and make shafts had a few made for tractors at work no complaints give them a try 0141 8832206.
Cheers
Stewart