I have seen this caused by three things. First bolts that are too long.
Second faulty bearings inside of the c/v joints on the half shafts that drive the rear wheels. The reason for the reverse only is they develope a burr in forward and change direction in reverse.
Third parking brake shoes. Make it duplicate the problem them hit the parking brake by 2 clicks and see what happens.

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Benzmac:
1987 16V
ASE CERTIFIED MASTER AUTO TECHNICIAN
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