Solved my C230 1998 rear end problem. Noise due to low lube and consequent scuffed pinion gear. Needed ear plugs to drive. So found a low mileage (38K) one at a specialty dismantler for $300. I contacted a local high school auto shop. The kids loved putting it in..less than 2 hrs with good instructor supervision. Simple job up on a lift. Just bolts to take out and install. Kids got $100 pizza/hamburger gift certificate. The local independent MB shop had quoted me $800 dollars to put it in and $1500+ for a new differential or $1000 for a used one. So now the car sound like brand new and the MB dealers didn't make out on my account.. :+)
Larry