ditto for me. I recently discovered while replacing the right rear parking brake cable that my remaned right rear caliper has the piston screw from a left rear in it. I can tell this because the caliper will lock up when pulling UP(cable at rest) on the cable arm. When pushing down(cable engaged) the rotor will spin freely. After fighting this for a while and doing for research, I discovered that this has been fairly common. I wish I would have realized this when I installed the caliper but I knew the cable was broke and didn't connect it until recently. I did get the left caliper adjusted and the parking brake set using the orge's instructions, and it holds somewhat, but 2 is better one.
so if anyone has an OLD right rear with CORRECT parking brake screw, let me know.