Just for the record:
At 180k, the rear control arm bushing on the right side was shot.
The other 3 were actually ok for whatever reason, but I replaced them all at once.
Balljoints seem due for replacement around 100k in my region.
Perhaps the roadsalt is a factor.

The control arm itself should not wear out- no moving parts.

Best of luck
Hope I can make it to 307k too!

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1986 300E 5-Speed 240k mi.