My 87 300TD developed a significant vibration that required braking or quick left right action to calm it down. The car had 185K and I was planning on changing the front suspension anyway. After taking it apart, no excessive wear or tell tale bushings worn, but the steering dampner was completely shot and leaking. Was not sure if it was caused by the vibration or was responsible. Left the shocks in since I had changed them 50k ago. Forgot to change the shock tower mounts and I wish I had. Everything is back to normal. Replace your steering dampner and see if it helps. An easy 1hr job and they are cheep.
Henry

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63 190d (sold)
69 220D (sold)
69 280SL (sold)
76 BMW 2002 (sold)
86 190E-16v (Demised at Laguna Seca Turn 9)
87 300SDL (sold)
87 300SDL 135k
87 300TD 280k (sold)
95 E320W 311k
95 E320w 180k
05 C320 4matic
06 E320 CDI 90k (Totaled by a texting 19 year old girl in a nissan)
2013 GLK 250 Bluetek 4MATIC 295k