I got a 7.5 with 3.73's from a 86 T-Type, bolted in my 84 Regal.

If its the Grand National or GNX I believe a 8.5 rear end was standard. Some Oldsmobile 442 models had the 8.5 also.. Other models had the 7.5. GM figured the tires would break loose before the... Login to read more.