This Dorman Brake Master Cylinder is designed for Chevy Chevrolet C50 C60 C70 P60 GMC Straight Truck - Medium Conventional, Stripped Chassis - Cab Forward Straight Truck - Low Tilt, System, Wagner FE57530, With Drum Brakes. It has a bore diameter of 1.5 inches and does not include a sensor. The rearward port thread size is 1/2-20 in. and it is sold individually. This product is a direct replacement with a lifetime warranty and fits various models and years ranging from 1980-1983, except for motor homes and with power brakes. The California Prop 65 Warning states that it may cause cancer and/or reproductive harm, so please read the proposition 65 warning before purchasing.