Used Aluminum GM Big Block Chevy, BBC, Boat, (Marine), High Rise Large Port, (Square Port), Intake Manifold with Brass Liners in the Water Passages to Prevent Corrosion in Salt Water Boat Applications, (GM Casting Number 6269318, GM Group Number 3.265). These intakes can also be used on cars, trucks, tractors, stationary engines, hot rods, rat rods, retro rods, mod rods, street rods, muscle cars, race cars, race trucks and many other applications. They are for short deck, (normal deck height), 396, 402 , 427, 454, 496 and 502 engines with large port heads. They can take either square bore or spread bore carburetors, (Holley and Rochester Quadrajets). You have to have adequate hood or engine bay cover clearance for the high rise is about the same height as all the GM Special High Performance Engines. This was used on Mercury Marine engines and others.