Up for sale is a used Smog Pump Pulley for a 1977-1980 GM H Body vehicles to include the Chevrolet Vega and Monza, Pontiac Astre and Sunbird, Buick Skyhawk and Oldsmobile Starfire. The pulley also fits all 1980 Cadillac model vehicles. The pulley is in good condition having been media blasted and painted black. The pulley shows some light pitting. GM part number 25504293 is stamped on the front of the pulley. The GM parts manual shows this pulley superseded part number 1254827. The parts manual also shows the pulley as having a diameter of 4 29/32”. The center shaft hole has a diameter of 1/2”.