This pump uses a 316L heat treated Stainless steel snout with a 17-4 hardened pump shaft and high speed roller bearings to provide the ultimate sea pump foundation for years of service. This pump is available in two (2) versions one which is the standard duty unit using a OEM style plastic impeller housing and impeller and a superduty version that employs Hardin's all stainless steel "Life Time" impeller housing with OEM Mercuiser impeller. The pumps are assembled and tested right here in the USA and are the best money can buy. Heavy Duty "Lifetime" Version Lifetime Series Stainless Steel Housing Hardin Stainless Steel Snout 17-4 Hardened Pump Shaft High Speed Roller Bearings Accepts OEM Factory Pulley Replaces Mercruiser #'s 46-807151A8 and 72774A82