1947 Chevy Truck. 1947 GMC Truck. Dual Master Cylinder for 1947-59 Chevy Truck. This is used with part numbers 71-984 47-54 and 71-985 55-59 to convert to a dual master cylinder. 1 1/8" bore. Forward outlet size is 1/2-20, and rear outlet size is 9/16-18.
