Sierra 18-1952-1 Manifold, MerCruiser, 99746A8, 65604A4. Precisely machined, painted and ready for installation right out of the box, Sierra manifolds help to keep engines running like new. Our selection of Sierra manifolds, risers and accessories is one of the most complete product lines in the marine aftermarket. Sierra's vast selection includes manifolds, risers, elbows and accessories for most every marine engine on the water today, including OMC/Volvo, Chrysler, Crusader, Pleasurecraft, Universal, MerCruiser and more. All parts are backed by Sierra's comprehensive warranty.Key FeaturesManufactured to match the original part and are fully interchangeable with the OEM products they are designed to replaceCNC machining assures that all components have a precise fitInclude all necessary gaskets and hardware for easy installationPrimed and painted for added durability and protectionComponents are ready to install out-of-the boxManifolds, risers and elbows are individually packaged in Instapack, an expanding packaging foam that keeps the part from chipping and breaking during transportationAll parts backed by SeaStar Solutions Two-Year Limited WarrantyHow to order the manifold you needClick on the dropdown menu above and select on the entry that includes the OEM number that matches your old manifold, elbow or riser. If you don't see it (or don't know the OEM number), proceed to our Sierra Online Parts Selector, where in addition to entering the OEM number, you can also search by engine manufacturer, model number, year, horsepower and serial number.