My ampmeter is pegging

Hi Guys,

I am having traouble finding a check valve for my Valiant. Does anyone know if power brakes were an option for the valiant signet in 1966? I am thinking someone might have installed a power booster and dual master cylinder and somepoint. I am looking for a 13/16 check valve and all I can find in a 1/2 inch valve.
Any clues?

Power brakes were an option in 66. If you have a dual M/C, it's already been upgrades as a 66 had a single M/C. I'll take a look at my spare check valves and see what I've got.