You only have 4 choices that I'm aware of. First is where the rotor and hub are one piece, the splines are incorporated into the rotor. Lots of folks are having problems with them, they are tearing out the splines because the cast iron is too soft. The 2nd is using a type 3 hub and a Porsche 914 rotor, this is by far the better way to go IMO. The 3ed is buying a big dollar aftermarket rear brake set up, some are good, some are not-so-good. The 4th is to make your own set up. Lot of guys have gone this route, I'm sure there are a bunch of options to do this. Someone will chime in on the way they did theirs. I made my own, well, because I could.