Greetings! I am in the same boat here (I think). Here are the details:

1. Shimmy/shake at around 55-65 MPH, but smooth up to 55 and (for the most part) after 65 MPH.
2. Tires were professionally balanced at independent MBZ mechanic who also tightened steering box
3. Verified new steering damper is still good

Were these the same symptoms for you? If so, I think I will be ordering a kit for both sides on mine and solve the problem! I am about to take it into the dealer nearby my work but would rather not for time and mostly financial reasons.

Thanks much,
Steve

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1996 Mercedes Benz S420 148K miles
1999 Volvo V70 Wagon 120K miles
1988 Chevrolet K1500 4x4 198K miles