This problem started when the zener changed his driveshafts so that might be a clue. A driveshaft that is a hair to long or possibly binding just a bit could be a problem.

OK, sorry I think I am getting zone5 and Zener mixed up!

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1988 325is (purchased new) sold
2004 X5 3.0 2005 X3 2.5
2008 X5 3.0 (new to me)