My sdl is doing the same thing- what weight of synthetic oil did you use in your rear diff. ?- i'm surprised that would make the difference- i was suspecting the center bearing on the driveshaft- by the way- anyone intersted in 1986 300sdl for sale? 215k miles- smoke silver w/burgundy leather- 17 years of ownership- it's a peach- give me a call- 207-632-6894