I work in a Mbz dealer bodyshop and while we see a smattering of W124's the majority of the cars affected are 1996-early 98 E-class(210) sedans. The spring perch kit used to be a welded on perch, now there is a whole perch and plate that is attached to the inner apron with rivets and epoxy structural adhesive. It's a quick and easy fix, all things considered. The ones we have seen tend to only rust on one side, and I really don't think it's all that widespread, statistically, although if it's your car, one is too many. The dealership where I work actively inspects for this when cars are in for other repairs and is very good about getting it fixed.

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2002 Ford ZX2
2 x 2013 Honda Civics