If your Mustang is not starting this switch could be at fault if the shifter rod is adjusted properly, if the transmission is in Park or Neutral selection. This also switch also operates the back up lights.
Fits:
1964 – 1966 Fairlane with column or console-shift C4 transmission
1965 – 1966 Falcon with column-shift C4 transmission
1964 – 1966 Galaxie / full-size Ford with column or console-shift C4 transmission
1965 – 1967 Mustang 8-cylinder with C4 transmission before 12/15/1966
1964 – 1966 Comet with C4 transmission
1967 Cougar with C4 transmission before 12/15/1966