As far as I have seen, I have to believe that all threads are the same size A, B, and E body. Some are smaller and others larger, but all have the same thread pitch to it's size. Call the place where you purchased the hose from to see if the part number given to you is correct. The fitting on the hard line could also be wrong. I've had more problems with new purchased parts that old stuff. Now they have brake line threads that are metric, could have been a mix-up at the manufacturer. The only thing different between power disc and manual drum is the master cylinder and proportional valve.