the wagner pn for the 4 bolt, 15/16" manual disc brake master is : F80266. check the piston bore for the rubber retainer groove, as it seems lately, this part# is used for both manual and power brake applications and may, or may not not have the retainer groove in the piston. in power applications, the groove is not needed. if you use a non grooved master in a manual application, you MUST make sure there is a positive, non moving, stop installed to prevent the pedal push rod from falling out of the master cylinder piston bore. as can be imagined, if the pedal push rod falls out of the piston bore, you may experience a very bad day. i don't know if the bendix or raybestos brand masters are set up the same way, but please check to make sure you know what you have and make any necessary adjustments as needed.