Thanks for yr reply.The master cylinder is definitely for drum brake application. I guess you could describe it as brake lock up. I don't know if I am just comparing my daily driver (2 yrs old) which is discs all round. Basically when talking to other owners at different meets who had drum / PB combo they all said their braking was much better & easier. Given I wanted to keep the vehicle as close to original as possible I found an old mustang Bendix booster from Griffs in Ballarat, had it rebuilt, installed it all & here we are.