Stainless steel resists corrosion and is ideal for thermostat housings The engines cooling system components take a beating. Constantly heat cycled and exposed to salt water and fresh water, these parts corrode at a much faster rate than other engine parts. Stainless steel is a great material to stand up to this abuse and will provide a longer service life. Sierra thermostat housings are engineered to match OEM housings to ensure technicians and boaters the fit and function will be to factory specifications. Each kit includes the necessary gaskets, plugs and spacers to complete the installation (see the instructions below to determine the correct spacer for your application). Key Features Stainless steel construction resists corrosion Engineered to OEM specifications for fit and function within factory specifications Kit includes housing, plugs, gaskets, and spacers required to complete installation Backed by SeaStar Solutions Limited Two-Year Warranty Sierra Part Number 18-1989 Application Table ApplicationOEM Part NumberMallory9-42500MerCruiser Sterndrive861006A1, 8M0061381The Sierra Engine Parts SelectorIn addition to thermostat housings, we offer a wide variety of other engine parts manufactured by Sierra. To see if we have the part you need, see ourEngine Parts Selector, where you can search by engine make, serial number and model or year of manufacture.Installation and Spacer Guide