The correct option if you are changing a Bugeye to front disc brakes, the ideal this is to change to the later backing plates which use a dual piston rear wheel cylinder and a nicer adjuster. The other option is to use this. This is the same as the wheel cylinder you use on a Bugeye, but it's 3/4" bore instead of 7/8". We've found that if you change to front disc brakes and leave the 7/8" rear wheel cylinders, the rears lock before the fronts. This should fix that problem. If you have these backing plates and still have the origional drums on the front, you need this wheel cylinder. This is AP brand.