1671 1966-1991 Chevy GMC 396 400 427 454 502 Long 7-1/4" PS Alt. mounts water pumpIs your big block running hot? Flowkooler designed a high flow water pump with a CNC machined billet impeller with 16 vanes, integrated shrouding and a reduced casting to impeller vane clearance. It achieves greater flow rates, higher head pressure and a more efficient flow. The impeller color is due to Type II Class II military grade surface coating which protects against corrosive fluids. FlowKooler introduced the first hi flow pumps and continues