The original master cylinders on these cars were units manufactured by Bendix for Ford. Attached are some variations that I have. They will all have a piston stop bolt in the center bottom versus the later replacements that do not have this. Master cylinders also have a date code stamped on the side of them and cast into the bottom related to the Julian calender (001 to 365)....so you would want to match that with your build date.
On the top side of the master cylinder the most noticeable is the dimple they have in the front left hand corner...most people I think look for this.
Rebuilding the original is always worth it if you want a concourse correct unit for your car. None of replacements are really close.
Depends on the condition of the master cylinder itself if it is worth rebuilding or if it can be rebuilt. Worst case is you would need to re-sleeve the unit if it is too pitted.
