Your rear suspension is shot, its commen on older MB's. Have a shop fix it its probably a number of worn parts.

I wouldn't bother with an alighnment, if the rear tires are wearing that badly all you have to do is look at the car to know something is up.

I'd start with new:
Rear shocks
springs and shims
diff mount
sway bar bushings and links.

Then take it from there, some of the subframe bushings are probably worn as well.

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2006 CL500
2009 C300 4matic
1969 280SE
2023 Ram 1500
2007 Tiara 3200