Hi I own a 1970 olds 2 DR 98 holiday coupe it has a BOP 12 bolt in it and a pond my investigation its a 12 bolt with a 9.375 ring gear 31 spline. A company by the name of JD race told me that this is a very big rear more then the car needs over kill but I want to keep the car original I'm looking for a limited slip or a posi unit for it new or used please does any one have any info for me it would be greatly appreciated.

 

Jim at JD Race would be your best source of information. He's one of our resident gurus and is a wealth of information on rearends for these cars.