vacuum brake help

[yruslow]

I bought a vacuum brake set up from kirbans a few years ago . Now I'm planning to switch my master cylinder. could anyone tell me what the diameter of the M/C might be without taking it off the car.

 

[novaderrik]

pull it off and measure the bore at the back with a caliper.

 

[Hot Air]

I bough a MC for a normally aspired V8 G-body...84-86 years. It came with a vacuum booster!
Conrad