Reverse gear set for ALL muncie 4 speeds, M20, M21, M22. This is a top quality mainshaft reverse gear and lower idler gear. Get both in this deal, or we do offer them seperatley in our web store as well. QUESTIONS? CALL TOLL FREE 1-877-614-4327 MONDAY THRU FRIDAY 8:00 A.M. TO 5:00 P.M. EASTERN TIME.