Does anybody know where I can obtain two sets of the external pistons (the piston that comes out of the wheel cylinder and pushes on the shoes, not the interal piston) for a 64-72 A body? o No: I pitched the originals when I tore my rear end down, thinking the new wheel cylinders would come with new ones. No such luck. I can't find them anywhere.
If you are talking about the pin that goes between the wheel cylinder piston and the brake shoe, HELP items should have them listed. They normally come two to a package. Any other brake hardware company should have them too. You may have to look in the pictures in the back of the book, but they will be there.