The booster mounts with a 4-bolt pattern. The 4 bolts are in a perfect square and are 3 3/8" apart (center to center). Mounting Brackets designed for your 1967 1968 1969 1970 1971 1972 Chevy Truck. The master cylinder in this kit is the Ball Milled style, 1" bore 9/16" and 1/2" ports each side.