{"product_id":"yukon-gear-muncie-m20-m21-bearing-kit-1963-1965-synchros","title":"Yukon Gear 63-65 Muncie M20\/M21 M\/T w\/SynchroS Bearing Kit","description":"\u003ch4\u003eEarly Muncie M20 and M21 Bearing and Synchronizer Kit for 1963-1965 GM Vehicles\u003c\/h4\u003e\n\u003cp\u003eThe Yukon Gear YUKZMBK117WS is a complete bearing kit with synchronizer rings engineered specifically for the Muncie M20 and M21 4-speed manual transmissions used in 1963-1965 GM performance vehicles. The early Muncie design used in these years differs in key bearing dimensions and synchronizer specifications from the more widely available 1966-and-later kits, making YUKZMBK117WS the correct choice for a proper rebuild of these early transmissions. Every bearing, race, and synchronizer ring required for a complete M20 or M21 rebuild is included from a single part number.\u003c\/p\u003e\n\n\u003ch4\u003eKey Features\u003c\/h4\u003e\n\u003cul\u003e\n\u003cli\u003eSpecifically engineered for the 1963-1965 Muncie M20 and M21 design\u003c\/li\u003e\n\u003cli\u003eOEM-specification bearings with correct load ratings for early Muncie dimensions\u003c\/li\u003e\n\u003cli\u003eCorrect friction-material synchronizer rings for the early Muncie synchronizer design\u003c\/li\u003e\n\u003cli\u003eComplete kit, no multi-supplier sourcing required\u003c\/li\u003e\n\u003cli\u003eRestores factory-quality shift feel and gear engagement\u003c\/li\u003e\n\u003cli\u003eLifetime limited warranty under the Magnuson-Moss Warranty Act\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch4\u003eSpecifications\u003c\/h4\u003e\n\u003ctable\u003e\n\u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eSpecification\u003c\/th\u003e\n\u003cth\u003eDetail\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003ePart Number\u003c\/td\u003e\n\u003ctd\u003eYUKZMBK117WS\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBrand\u003c\/td\u003e\n\u003ctd\u003eYukon Gear \u0026amp; Axle\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTransmission Application\u003c\/td\u003e\n\u003ctd\u003eMuncie M20 \/ M21 4-speed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFitment Years\u003c\/td\u003e\n\u003ctd\u003e1963-1965\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eIncludes Synchros\u003c\/td\u003e\n\u003ctd\u003eYes\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWarranty\u003c\/td\u003e\n\u003ctd\u003eLifetime limited\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eUPC\u003c\/td\u003e\n\u003ctd\u003e883584297125\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch4\u003eFitment\u003c\/h4\u003e\n\u003ctable\u003e\n\u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eYear\u003c\/th\u003e\n\u003cth\u003eMake\u003c\/th\u003e\n\u003cth\u003eModel\u003c\/th\u003e\n\u003cth\u003eNotes\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e1963\u003c\/td\u003e\n\u003ctd\u003eChevrolet\u003c\/td\u003e\n\u003ctd\u003eCorvette\u003c\/td\u003e\n\u003ctd\u003eMuncie M20 or M21 4-speed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e1964\u003c\/td\u003e\n\u003ctd\u003eChevrolet\u003c\/td\u003e\n\u003ctd\u003eCorvette\u003c\/td\u003e\n\u003ctd\u003eMuncie M20 or M21 4-speed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e1965\u003c\/td\u003e\n\u003ctd\u003eChevrolet\u003c\/td\u003e\n\u003ctd\u003eCorvette\u003c\/td\u003e\n\u003ctd\u003eMuncie M20 or M21 4-speed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e1964\u003c\/td\u003e\n\u003ctd\u003eChevrolet\u003c\/td\u003e\n\u003ctd\u003eChevelle\u003c\/td\u003e\n\u003ctd\u003eMuncie M20 or M21 4-speed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e1965\u003c\/td\u003e\n\u003ctd\u003eChevrolet\u003c\/td\u003e\n\u003ctd\u003eChevelle\u003c\/td\u003e\n\u003ctd\u003eMuncie M20 or M21 4-speed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e1963\u003c\/td\u003e\n\u003ctd\u003eChevrolet\u003c\/td\u003e\n\u003ctd\u003eNova\u003c\/td\u003e\n\u003ctd\u003eMuncie M20 or M21 4-speed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e1964\u003c\/td\u003e\n\u003ctd\u003eChevrolet\u003c\/td\u003e\n\u003ctd\u003eNova\u003c\/td\u003e\n\u003ctd\u003eMuncie M20 or M21 4-speed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e1965\u003c\/td\u003e\n\u003ctd\u003eChevrolet\u003c\/td\u003e\n\u003ctd\u003eNova\u003c\/td\u003e\n\u003ctd\u003eMuncie M20 or M21 4-speed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e1963\u003c\/td\u003e\n\u003ctd\u003eChevrolet\u003c\/td\u003e\n\u003ctd\u003eImpala\u003c\/td\u003e\n\u003ctd\u003eMuncie M20 or M21 4-speed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e1964\u003c\/td\u003e\n\u003ctd\u003eChevrolet\u003c\/td\u003e\n\u003ctd\u003eImpala\u003c\/td\u003e\n\u003ctd\u003eMuncie M20 or M21 4-speed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e1965\u003c\/td\u003e\n\u003ctd\u003eChevrolet\u003c\/td\u003e\n\u003ctd\u003eImpala\u003c\/td\u003e\n\u003ctd\u003eMuncie M20 or M21 4-speed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e1964\u003c\/td\u003e\n\u003ctd\u003ePontiac\u003c\/td\u003e\n\u003ctd\u003eGTO\u003c\/td\u003e\n\u003ctd\u003eMuncie M20 or M21 4-speed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e1965\u003c\/td\u003e\n\u003ctd\u003ePontiac\u003c\/td\u003e\n\u003ctd\u003eGTO\u003c\/td\u003e\n\u003ctd\u003eMuncie M20 or M21 4-speed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e1963\u003c\/td\u003e\n\u003ctd\u003ePontiac\u003c\/td\u003e\n\u003ctd\u003eTempest\u003c\/td\u003e\n\u003ctd\u003eMuncie M20 or M21 4-speed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e1964\u003c\/td\u003e\n\u003ctd\u003ePontiac\u003c\/td\u003e\n\u003ctd\u003eTempest\u003c\/td\u003e\n\u003ctd\u003eMuncie M20 or M21 4-speed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e1965\u003c\/td\u003e\n\u003ctd\u003ePontiac\u003c\/td\u003e\n\u003ctd\u003eTempest\u003c\/td\u003e\n\u003ctd\u003eMuncie M20 or M21 4-speed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch4\u003eWhat's Included\u003c\/h4\u003e\n\u003cul\u003e\n\u003cli\u003eInput shaft bearing\u003c\/li\u003e\n\u003cli\u003eCountershaft (cluster gear) bearings\u003c\/li\u003e\n\u003cli\u003eOutput shaft pilot bearing\u003c\/li\u003e\n\u003cli\u003eAll synchronizer rings\u003c\/li\u003e\n\u003cli\u003eSnap rings and small parts\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch4\u003eFrequently Asked Questions\u003c\/h4\u003e\n\u003cp\u003e\u003cstrong\u003eWhy is a separate kit needed for 1963-1965 versus 1966-and-later Muncie transmissions?\u003c\/strong\u003e\u003cbr\u003eThe 1963-1965 Muncie uses different bearing dimensions and synchronizer ring specifications compared to the revised design introduced for 1966. Using the wrong kit results in incorrect bearing clearances and mismatched synchronizer friction surfaces, which causes premature wear and poor shift quality.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow do I confirm I have a 1963-1965 Muncie M20 or M21?\u003c\/strong\u003e\u003cbr\u003eThe date code is stamped on the transmission case. Codes from 1963 through early 1966 production identify the early design. The serial number prefix also identifies M20 versus M21. Verify your code before ordering to avoid using an incorrect kit.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDoes YUKZMBK117WS include synchronizer rings for all gears?\u003c\/strong\u003e\u003cbr\u003eYes. All synchronizer rings for every gear position are included in the kit.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eIs the M22 Rock Crusher covered by this kit?\u003c\/strong\u003e\u003cbr\u003eNo. The M22 was introduced after the early-production Muncie design era covered by this kit. The YUKZMMK116WS covers the 1966-1974 M22.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat warranty does Yukon provide on this bearing kit?\u003c\/strong\u003e\u003cbr\u003eYukon Gear backs YUKZMBK117WS with a Lifetime Limited Warranty. As a drivetrain rebuild component, consumer protections under the Magnuson-Moss Warranty Act apply.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I reuse the original synchronizer hubs and sliders?\u003c\/strong\u003e\u003cbr\u003eIt depends on wear. Hubs and sliders should be inspected carefully for indexing wear, cracks, and shift groove damage. In most cases, worn synchronizer rings are the primary failure point, but badly worn hubs and sliders will quickly destroy new rings.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat gear oil should I use after rebuilding with this kit?\u003c\/strong\u003e\u003cbr\u003eThe Muncie requires GM Synchromesh or an equivalent MT-90 fluid. Conventional gear oil and limited-slip additives will damage the brass synchronizer rings in this transmission.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eAre the bearings in this kit branded or generic?\u003c\/strong\u003e\u003cbr\u003eYukon sources bearings to OEM-grade specifications. The bearings are manufactured to meet or exceed the load ratings and dimensional tolerances of the original equipment components.\u003c\/p\u003e\n\n\u003ch4\u003eInstallation Notes\u003c\/h4\u003e\n\u003cul\u003e\n\u003cli\u003eConfirm the transmission date code identifies a 1963-1965 Muncie M20 or M21 before ordering\u003c\/li\u003e\n\u003cli\u003ePress all bearings into position; do not use a hammer directly on bearing races\u003c\/li\u003e\n\u003cli\u003eInspect synchronizer hubs, sliders, and shift forks for wear beyond acceptable limits during disassembly\u003c\/li\u003e\n\u003cli\u003eReplace all snap rings with new items from the kit\u003c\/li\u003e\n\u003cli\u003eFill to capacity with GM Synchromesh or MT-90 equivalent after the rebuild is complete, and check for leaks before returning to service\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch4\u003eCalifornia Prop 65 Warning\u003c\/h4\u003e\n\u003cp\u003eWARNING: This product can expose you to chemicals including lead and lead compounds, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.\u003c\/p\u003e","brand":"Yukon Gear \u0026 Axle","offers":[{"title":"Default Title","offer_id":45974398992463,"sku":"YUKZMBK117WS","price":138.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1062\/7920\/files\/yukon-gear-zmbk117ws-muncie-m20-m21-bearing-kit.png?v=1782661335","url":"https:\/\/www.blackopsautoworks.com\/products\/yukon-gear-muncie-m20-m21-bearing-kit-1963-1965-synchros","provider":"Black Ops Auto Works","version":"1.0","type":"link"}