As to the limited slip differential, I also know that it was supposed to be standard equipment on the 1991 turbo cars. However the 123,xxx mile wrecked 1991 745T that I bought the engine out of so cheaply ($125, less turbo), had the 1031 rear end instead of the 1041 it was supposed to have. I don't think the rear end had been changed, I think Volvo installed the Eaton Locker as a running modle year change. This car was made early enough not to have it. I looked very closely at the rear end, looking for another bargain.