Welcome to the Bolt!
Nice truck!
1957 Shop Manuals are being reproduced and sold by most of the vendors for about $30.
Have you looked the brakes over enough to tell what type of system you have? Do you have a standard hydraulic master cylinder with a Air Over Hydraulic booster mounted on the frame rail or do you have a air brake treadle pedal that puts air on a air chamber that has the master cylinder attached to it? If you have a treadle pedal, that's not a factory installed system in your truck.
Brake parts can be found at your local BiG truck parts house and places like Rock Auto (online) and NAPA.
Mike B
