{"product_id":"sierra-18-6406-marine-u-joint-for-mercruiser-stern-drive-gkn-series-serial-ol100009-and-up-replaces-mercury-865493a01","title":"Sierra 18-6406 U-Joint Assembly, Replaces 865493A01\/865496A01, for Mercruiser Alpha I, Alpha I SS \u0026 Bravo Stern Drives","description":"\u003cp\u003eThe Sierra 18-6406 U-Joint Assembly is a replacement universal joint built for Mercruiser stern drive units, connecting the drive shaft to the transmission and lower unit so power transfers smoothly through the drive's articulation points. A worn or failing U-joint can cause vibration, clunking, or play in the drive train, and replacing it with a properly fitted assembly like the 18-6406 restores smooth, reliable power transfer.\u003c\/p\u003e\u003cp\u003eThis assembly includes both a straight and a 90 degree grease fitting, giving the installer flexibility to choose the fitting orientation that best suits the access and grease gun setup on the specific installation. It is designed to fit Mercruiser Alpha I units from serial number B418819 and above, as well as Alpha I SS and Bravo drives, making it a common service part for these Mercruiser drive families.\u003c\/p\u003e\u003cp\u003eThe 18-6406 cross-references directly to Mercury Marine OEM part numbers, so it can be used as a like-for-like replacement on applicable Mercruiser units without altering fit or function versus the original equipment part.\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 18-6406\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Name:\u003c\/strong\u003e U-Joint Assembly\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIncludes:\u003c\/strong\u003e Straight grease fitting and 90 degree grease fitting\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFitment:\u003c\/strong\u003e Mercruiser Alpha I (S\/N B418819 and above), Alpha I SS, Bravo\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 1.04 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282182618\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eMercruiser Alpha I units, serial number B418819 and above\u003c\/li\u003e\n\u003cli\u003eMercruiser Alpha I SS\u003c\/li\u003e\n\u003cli\u003eMercruiser Bravo\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e865496A01\u003c\/li\u003e\n\u003cli\u003e865493A01\u003c\/li\u003e\n\u003cli\u003e865510T\u003c\/li\u003e\n\u003cli\u003e865511T\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat does the Sierra 18-6406 U-Joint Assembly fit?\u003c\/strong\u003e It is designed for Mercruiser Alpha I units with serial number B418819 and above, as well as Mercruiser Alpha I SS and Bravo stern drives.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhich OEM part numbers does the 18-6406 replace?\u003c\/strong\u003e The 18-6406 replaces Mercury Marine OEM numbers 865496A01, 865493A01, 865510T, and 865511T.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-6406 a direct equivalent to the Mercury Marine 865493A01 and 865496A01 U-joints?\u003c\/strong\u003e Yes, the Sierra 18-6406 U-Joint Assembly cross-references directly to Mercury Marine 865493A01 and 865496A01, so it installs as a like-for-like replacement on applicable Mercruiser drives.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat grease fittings come with this U-joint assembly?\u003c\/strong\u003e The 18-6406 U-Joint Assembly includes both a straight grease fitting and a 90 degree grease fitting, so the installer can choose whichever orientation fits the available access.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-6406 U-Joint Assembly weigh?\u003c\/strong\u003e The Sierra 18-6406 U-Joint Assembly weighs 1.04 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill this U-joint work on any Mercruiser Alpha I drive?\u003c\/strong\u003e It fits Mercruiser Alpha I units from serial number B418819 and above; earlier serial number Alpha I units are not covered by this listing, so check the drive's serial number before ordering.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-6406 fit Bravo drives as well as Alpha units?\u003c\/strong\u003e Yes, in addition to Alpha I (S\/N B418819 and above) and Alpha I SS, the 18-6406 U-Joint Assembly also fits Mercruiser Bravo drives.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-6406 a genuine OEM part or an aftermarket replacement?\u003c\/strong\u003e The 18-6406 is a Sierra-branded replacement U-joint assembly engineered to replace the listed Mercury Marine OEM numbers, rather than a Mercury-branded original part.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is included in the box with the 18-6406 U-Joint Assembly?\u003c\/strong\u003e The assembly ships complete with the U-joint and its two grease fittings, a straight fitting and a 90 degree fitting.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhy would I need to replace the U-joint on my Mercruiser stern drive?\u003c\/strong\u003e A worn U-joint assembly like the one replaced by the Sierra 18-6406 can develop play or wear at the drive shaft connection, and replacing it restores proper alignment and power transfer between the transmission and the lower drive unit.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988357460187,"sku":"SIE-18-6406","price":125.28,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-6406_lg__35158.1558129377.500.750.jpg?v=1785189100","url":"https:\/\/www.goodvibesmarina.com\/products\/sierra-18-6406-marine-u-joint-for-mercruiser-stern-drive-gkn-series-serial-ol100009-and-up-replaces-mercury-865493a01","provider":"Good Vibes Marina","version":"1.0","type":"link"}