The rear trailing arms can be bent; I bent the right rear trailing arm on my 126 280SE during a Wisconsin winter when I spun out and hit a curb years ago. I didn't think the impact was that bad, but the camber on that wheel after the epsisode was out of wack. I replaced the arm with a used one and everything was back to normal. There were no signs stress on on bent arm.

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as ever
Paul

1989 560SL
1987 300SDL
1987 300TD
1983 BMW 633CSi
1972 280SE 4.5