I would check two things: your engine mounts and your transmission fluid.

If the engine mounts are gone, put in new ones.

If you have not serviced the transmission, have it done a.s.a.p. (oil and filter change) Disregard the theory about the oil for the 722.6 being set for life. And remember to use only the authorized M.B. oil and be sure that the level is fill up to the top mark. Also, be sure the level is properly checked after refill at the appropiate oil temperature.

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A. Rosich
CL 500, 1998
S 500 L, 1998
E 320 T, 1995 [Sadly sold ]