Identify Disc Brakes on Dart?

70-74 Challenger is an E-body, and they are all big bolt pattern. It's sister E-body car was the 70-74 Barracuda, which was also big bolt pattern.
I believe all early, and some later A-body 63-"about" 72 cars came with small bolt pattern, drum and 4-piston disk brakes. The gray area comes when Ma Mopar began to install the single-piston floating caliper disks around '73(I think). They changed to BBP on the A-body cars with the optional single-piston floating caliper installation. Of course, in order to have BBP rear wheels to match, those cars had to come with BBP rear axles. I THINK, they came with the so-called 8-1/4" rear axle. I don't think there ever was an OEM A-body BBP 8-3/4" rear axle. I believe at some point, maybe '75 they ran out of all the SBP drums, and axles and ALL the last A-bodies came with just BBP.