Chevrolet Small Block short style water pump. 5.625 inch hub height, 3/4 inch Bearing, 3/4 inch Shaft, Cast Aluminum Finish, 3/8 inch NPT outlets. ?The Stage 4 water pumps have the same features as the Stage 3 plus they incorporate the all new DRV-series 8 vane CNC machined 6061-T6 billet aluminum impellers. Developed by Stewart Components, these impellers flow up to 41% more water at twice the pressure than traditional designs... while consuming less horsepower. The ultimate water pump for any racing application.