[Rory McNeil]

Like Larry said, at least on Fords, the manual brake cars came with a different brake pedal, with a pivot for the master cylinder pushrod closer to the pivot for the pedal itself, for more mechanical advantage. Again, with my Fords, manual master cylinders a re usually a smaller bore, like 7/8" or 15/16" diameter, compared to over 1" for a power brake application.