Muncie Transmission Case, #3925661
1970-74 Muncie M-20 M-21 M-22 Transmission Case #3925661. You can now replace your damaged or broken M-20, M-21 or M-22 transmission case with this new OEM factory case. This case has 3925661 with U.S. PATENT and GENERAL MOTORS CORP. cast on it. Both fill and drain plugs are drilled and tapped. This is a licensed General Motors part.