Thought I had a differential going bad, contstant growling, grabbing/dragging noises coming from that area. Put it up on the lift and found the driver side rear wheel had a BUNCH of wobble and play. After reading here on the forum about how hard a job it was to pull and replace these, I opted to have our local Mercedes Indy do the work.
This was the first big job I've had someone else do on this car. I felt a little lazy, but when we picked the car up the shop owner told us that his wrists and shoulder we're going to ache all weekend from the bearing removal. Wow.
While it was there I had them fine tune the injection pump timing. Last year I replaced the original with a remanufactured unit. Got it close enough to run, but I knew it could be better. They charged me one hour of shop time. That was the best $90 I ever spent! Wow again. The car runs like a sewing machine now.
Though the whole job cost me some money, to have it back and running (and sounding) great again it was worth it.