I found my Dad a 1990 MB 300SE. The car had a complete tune up, new motor mounts, all fluids changed, new O2 sensor and more work. The front end was repaired with new ball joints and tie rod ends and is now tight. A few issues still linger. The most important one is a slight whine in the rear end area. When we test rode the car I sat in the back seat and in the front. The whine is louder in the back seat but when driving I can still hear it. Can someone give me an estimate to have the differential replaced with a rebuilt unit? I am frequesntly wrong but I thought I read somewhere that rebuilt differentials basically right bolt in and cost around ~$300. Not inlcuding labor of course.. The interior is very nice and it seems everything works except the cruise control, but I am still reading the original owner's manual and might not know how to turn it on right yet. So can someone who has had a differential replaced in a S-class 126 body give me a estimate of the cost of the repair. I am also not sure about the shop we are now using. He strongly hinted to me that bolting in a used salvage yard used differential is the way to go. I would think a rebuilt unit would be more reliable since I would know they are not bolting in a used differential with 400K miles into the car.. I am at the point where we can still sell the car with records and recover the cost of repairs and then move on. In fact I am now looking very hard at MB diesel cars. I am still learning as I have always owned faster cars. But finding a nice MB car for my Dad is what this is all about. Thanks people for taking the time to read this. John from MA