The 1964-1966 Mustang 7" Zinc Single Diaphragm Brake Booster requires 18" of vacuum to operate properly. With this vacuum level the booster will produce a maximum pressure output of 950 PSI with a 1" bore master cylinder. This pressure level will work great for four wheel drum systems and disc/drum vehicles which are relatively light.
This booster is not recommended for heavy disc brake cars or any four wheel disc brake system. This is the booster supplied with our under floor pedal kits.