As an added bonus, if the 7 1/4 is bbp, it gets the same 10'' brakes and backing plates as a 8 1/4.
All 7 1/4 rears that were sbp had the lousy 9'' brakes.
As a rule of thumb, all 4 doors, swingers, and scamps were 111'' wheelbase.
Dusters and Dart Sports were 108'' wheelbase.
Bbp was available only in '73 and newer a body cars with disc brakes.
All V8 cars '73 and up had bbp disc brakes and rear ends. 318 cars could have a 7 1/4 bbp or a 8 1/4 bbp and could have a 904, 727, or standard trans. All 340 and 360 cars had power bbp discs, a 8 1/4 bbp rear end and a 727 auto or a standard trans.
If a '73 and up slant 6 car was ordered with power brakes, it automatically had bbp discs on the front and probably had a 7 1/4 rear end, which was of course bbp. Slant 6 cars generally came with a 904 auto or a standard trans.
All slant 6 cars '73 and up came with sbp 9'' brakes and a sbp 7 1/4 to match unless you ordered power brakes.
So, it adds up that if you are putting in a 7 1/4 bbp rear end in your car and your car was originally a 7 1/4 sbp, the drive shaft will be the same as in your car now.
If you add a 8 1/4 rear end (all of them were bbp), take the drive shaft and rear end from a car that matches your wheel base. In this case, make sure that the transmission is the same and it will bolt in, drive shaft and all.
