Hi.
I have a 230SL.
There was a whining sound coming from the differential at speeds above 40 kmph. Nothing below that. We opened the differential and replaced all the bearings including wheel bearings. Now the whining stopped but a new sound started ... that of gears ... This sound starts at lower speeds of 10 kmph and continues as we drive the car. We once again opened the differential and replaced the crush sleeve on the pinion and the nut. Tightened the nut fully and took a trial. The noise is reduced but not yet gone. Tried to tighten the nut further but was not possible. How to proceed now is the question?