When we read the instructions for the rear brake kit, we found that we had to modify the OE axles and hub a bit. Depending on what type of 12-bolt rear end and axles each car is equipped with, the outer hub might need to be machined down in order to fit into the disc brake hub. Not all 12-bolts are exactly the same. Luckily, we had a lathe handy. While we were at it, we replaced the studs with newer, longer wheel studs. No matter what, the axles will have to be removed in order to install the new rear rotors.