It sounds and feels like a total loss of rear suspension yet I am sure it is not shocks or springs. Could it be inside the rear end or have something to do with some type of arm? It seems to disappear for days at a time then suddenly reappear. I took it to an official Mercedes dealer but their mechanics don't have enough experience with older cars. At 160 dollars per hour they would love to have me there for days at a time. They claimed the problem is a rear wheel bearing but it makes no sense to me. Anyone been through this before? Suggestions?