This is a brand new Authentic General Motors heavy duty counter-rotation marine base engine. This 5.7L Marine engine is built strictly for marine use on GM production lines. The price includes intake manifold gaskets. The 5.7L L31 is the premier industrial workhorse, providing the power needed to get the job done without sacrificing fuel efficiency or durability. Includes: Vortec Engine with High Flow Cylinder Heads, Harmonic Balancer, Oil Pan, Valve Covers, Spark Plugs, and Intake Manifold Gasket Kit. Replaces MerCruiser: 8M0088397, 866138A03, 807449R5, 807449R50, 863661R5, 8M0124238, 866138R03, 8M0124033, and Volvo Penta 3801527.