I have a 1990 300E 3.0 4 matic with 113,000 miles. Pretty much in excellent condition. I have noticed though a loud crunching noise coming from the right rear area, when going over a dip in the road.
If you have ever driven in snow, and had it accumulate in your wheel wells, and it crunches when the tire hits the snow or ice, this is what it sounds like.
The shocks, and springs seem to be fine. The car sits, and drives perfect. Could it be some kind of bushing or something?