Master Cylinder for 66 Formula S

I believe one can use any manual disk/drum MC four stud mount from later cars such as A body, and F body. The newer MC’s have larger bowls, and a choice of bore size. I installed Raybestos 36412 with 1 1/32” bore which works well with four piston KH front disks on my 1967 Dart. Later model single disk stile calipers may work easer with smaller bore MC. It has to do with the ratio between MC piston area to Caliper piston area as to how easy pedal feels.

If you have 10 inch rear drums, consider installing smaller diameter wheel cylinder than factory used to lessen premature rear wheel lock up such as Napa 37676 or Raybestos 37696. Back in the day factory fitted cop cars with these smaller cylinders to keep them from doing 180* spins during hard braking.

You can read more about MC & wheel cylinder choices to use for converting from single pot to duel pot at that other site “slantsix dot org” authored by slantsixdan using “Search” function.