Re: the fenco. The first master I started with was from my local Autozone. It had a bolt in the middle to hold the cap on, but the biggest issue I had(and it looks to be the same in the above pic) is that there was a tab on the mating surface to hold the piston in the master. To use that master, I'd need to trim the firewall for clearance. That didn't seem to me something I should need to do for a "replacement" part. Maybe I was wrong?