On a 603. Just curious. After replacing the front tires on my 87 300D, my neverending highway vibration reduced quite a bit (and the noise is gone!), but I'm definitely still getting a shake in the steering wheel and slight vibration in the floorboard, intermittently between 55-70. It seems to be most noticeable on acceleration, and is (in my nonscientific estimation) more often to occur while going up a very slight incline.
I noticed some very tiny cracks in the motor mounts and I'm wondering if it could be them starting to go? They were replaced 50,000 miles ago (five years). The transmission mount, as far as I know, has never been replaced, so I'm going to do that. Would it be wise to do the motor mounts while I'm at it, or a waste? For whatever it's worth, idle and low speeds are super smooth.

As a side question ... the rear linkage on this car is a disaster, and the diff bushings (in the back, that hold it on the subframe) are shot. I plan to have my indy do that job when I get back from London in the fall (technically I can do it, but physically I don't think I can by myself). Can those problems in the rear manifest in vibrations in the front?

Poor Bodhi, this has not been his year. Guess it could sure be worse. At least I've gotten some things solved along the way.

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1987 300D, arctic white/palomino--314,000 miles
1978 240D 4-speed, Euro Delivery, light ivory/bamboo--370,000 miles
2005 Jeep Liberty CRD Limited, light khaki/slate--140,000 miles
2018 Chevy Cruze diesel, 6-speed manual, satin steel metallic/kalahari--19,000 miles
1982 Peugeot 505 diesel, 4-speed manual, blue/blue, 130,000 miles
1995 S320, black/parchment--34,000 miles (Dad's car)