mongrel bike. Most likely was FX. Here's the pic. Has date etched in it, sep 1972. I was thinking GMA but not that sure. I should probably replace it but...

 

PM = performance machine

 

thanks for resolution Joe12RK.

 

They still sell the rebuild kit for those. Had 3 custom riigid frame bikes. Ran that rear on all three. PM makes a beefier set up now but those will still work fine for waht you have.

 

80's Performance Machine with the bigger dual pistons instead of the 4 piston like the later version . Older Jay Brake stuff was the same size brake pads & puck o-rings . Polish it up a bit and run it