Mt 1985 300D does the same thing, and I have replaced the half shafts, flex discs, rear rtanny mount, motor mounts, center bearing and support, and yet the noise remains. I believe it to be in the ring gear and pinion in the differential. I have decided to live with it and accept it, as it isn't that bad. I recommend jacking your car up and having a guy hold one rear tire as you try to rotate the other back and forth to see how much play there is. I'm not sure how much is too much but you will possibly be able to duplicate the problem this way. another area might be the differential mount or even the rear tranny mount. good luck, isn't it fun to track down all these things? no ride is better than in Benz. thanks, adam