have anyone experienced the prop shaft (long shaft) universal joint replacement before?any in service experience...good or bad and how is it after replacement.does it last or are there any vibrations induced after the change? i've had mine done on the e34 (both center and rear U joint) and so far so good but i cannot say the same for my e30...i'm on my third rear U joint.symptoms are knocking sound @ no load as there are a bit of play in the U joint bearing.also the whole car vibrates at speeds in excess of 160km/h which till today (after 4 yrs ownership) I am still not able to determine the cause. and 1 more thing,if we separate the prop shaft halves,do we really need to join them up at exactly the same previous position to ensure they are balanced?i notice that they individually have balancing weights welded on them so logically either half can be assembled at any position to each other?