There is a procedure to put the proper tension on the center bearing (slotted holes) when installing it. There is no spline, just the guibo on the front portion of the driveshaft to take up any misalignment issues which might be worse if engine/trans mounts are worn etc.

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