It has a 1 9/16" port and 1/2" port. This will work with most after market brake boosters used on 1955-1974chevrolet cars. The ports are drilled on the left side.
For Chevy A/F/X GM AC Delco Style Chrome 11" Single Diaphragm Brake Booster
AC Compressor with Clutch & 2-Groove for Sanden 508 Style V-Belt Chrome Aluminum
Chrome Aluminum Long Water Pump for Chevy Big Block V8 396-454 69-87 Long Style
GM Style 23" X 19" Universal Aluminum Racing Radiator Heavy Duty Extreme Cooling
Holley 20-119, One Black Aluminum Gm Style Kickdown Detent Cable Brkt For #Fits
SD7176 Style Peanut Style Chrome A/C Compressor 8 Groove Serpentine Belt R134A