{"product_id":"sierra-18-6401-yoke-assembly-for-mercruiser-1-r-mr-alpha-one-gen-ii-1971-1997-replaces-814819a2-59830a5-59829a1","title":"Sierra U-Joint Assembly 18-6401 for Mercruiser, Replaces Mercury Marine 864244A2, 12784A10","description":"\u003cp\u003eThe Sierra U-Joint Assembly, part number 18-6401, is a machined replacement universal joint assembly engineered for Mercruiser sterndrive applications. It is designed as a direct cross-reference replacement for Mercury Marine universal joint assemblies, allowing boat owners and marine technicians to restore proper drive-line articulation between the engine coupler and the sterndrive without sourcing a discontinued or hard-to-find OEM part.\u003c\/p\u003e\u003cp\u003eThis U-joint assembly features a machined exterior finish for consistent fit and smooth operation under the torsional loads typical of sterndrive power transfer. It is built to Sierra's standard for Mercruiser U-joint and yoke components, making it a straightforward swap for technicians already familiar with servicing Mercruiser drive-line hardware.\u003c\/p\u003e\u003cp\u003eBecause drive-line components like this carry significant rotational load, the assembly is constructed as a substantial, solid unit rather than a lightweight stamped part. Boat owners replacing a worn, notchy, or failed U-joint should confirm their existing part matches the Sierra 18-6401 or one of its OEM cross-reference numbers before ordering.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-6401\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Name:\u003c\/strong\u003e U-Joint Assembly\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCategory:\u003c\/strong\u003e Mercruiser U-Joints and Yokes\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 10.94 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Dimensions:\u003c\/strong\u003e 0.39 x 0.39 x 0.39 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExterior Finish:\u003c\/strong\u003e Machined\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282111830\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross Reference:\u003c\/strong\u003e 864244A2, 12784A10\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cp\u003eDesigned for Mercruiser sterndrive U-joint and yoke applications.\u003c\/p\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e864244A2\u003c\/li\u003e\n\u003cli\u003e12784A10\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat is Sierra part number 18-6401?\u003c\/strong\u003e It is a U-Joint Assembly designed for Mercruiser sterndrive applications, providing the universal joint connection used in the drive-line between the engine coupler and the sterndrive.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the Sierra 18-6401 replace Mercury Marine parts?\u003c\/strong\u003e Yes, the Sierra 18-6401 U-Joint Assembly cross-references to Mercury Marine part numbers 864244A2 and 12784A10.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-6401 U-Joint Assembly weigh?\u003c\/strong\u003e The Sierra 18-6401 U-Joint Assembly weighs 10.94 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat are the dimensions of the 18-6401 U-Joint Assembly?\u003c\/strong\u003e The listed product dimensions for the Sierra 18-6401 are 0.39 x 0.39 x 0.39 inches.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat finish does the 18-6401 U-Joint Assembly have?\u003c\/strong\u003e The Sierra 18-6401 has a machined exterior finish.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-6401 an OEM part or an aftermarket replacement?\u003c\/strong\u003e The Sierra 18-6401 is an aftermarket U-Joint Assembly manufactured by Sierra as a direct cross-reference to Mercury Marine OEM part numbers 864244A2 and 12784A10.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat application is the 18-6401 U-Joint Assembly used for?\u003c\/strong\u003e It is categorized for Mercruiser U-joints and yokes, used in the sterndrive coupling of Mercruiser-equipped boats.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow do I know if I need the Sierra 18-6401 U-Joint Assembly?\u003c\/strong\u003e If your existing U-joint assembly carries the Mercury Marine part number 864244A2 or 12784A10, or shows wear such as play or roughness in the joint, the Sierra 18-6401 is the correct cross-reference replacement.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-6401 currently in production?\u003c\/strong\u003e Yes, the Sierra 18-6401 U-Joint Assembly is not discontinued by the manufacturer.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-6401 U-Joint Assembly?\u003c\/strong\u003e The UPC for the Sierra 18-6401 U-Joint Assembly is 808282111830.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988359426267,"sku":"SIE-18-6401","price":609.68,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/18-6401__33486.1741557358__05481.1753473616.500.750.jpg?v=1785189211","url":"https:\/\/www.goodvibesmarina.com\/products\/sierra-18-6401-yoke-assembly-for-mercruiser-1-r-mr-alpha-one-gen-ii-1971-1997-replaces-814819a2-59830a5-59829a1","provider":"Good Vibes Marina","version":"1.0","type":"link"}