You can firstly see if the shafts are aligned up with their marks and I believe its safe to assume you are using a good quality bearing mount rubber.

The sleeve nut should be tightened to approx 30 lb/ft with about a tablespoon of axle grease on the shaft splines and about a teaspoon in the centering bushings. The shaft should be able to slide a bit in and out with some force.

If you do a google search (might have to even search via google.de) you will find some similar problems, this is usually experienced by ML owners too but their solution is to buy a MB part which is actually a spicer brand center bearing and support.

MB also provided extensive procedures to remove such vibration from the driveline for the sedans, it also included shimming the carrier bearing so that the shaft sits a bit straight and also include some weighted nuts for the D/shaft bolts.

There was a thread on these forums where a user experienced an out of round flex disc causing problems.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)