8.25 "a"

The 8 1/4 rear became the std rear axle on 73 and up 340/360 A bodies. Not rare at all, and allways cheaper than a 8 3/4.

Sorry. For some reason, I was thinking he needed SBP (I was just in the early A forum). Now I realize the OP didn't tell us what year the car is. It usually matters.