Fairbanks-Morse Magneto Fiber Gear Y5939 FMX4B16A-1 This gear fits Allis Chalmers with FMX-4B3 IHC/Farmall with FMX-4B11 Wisconsin AC4, ACY, AC4S, AM4, AP4, B2, B3, K2, K2A, SD45, SU, VG4D, VH4, W, X,  Y97 with Fairbanks-Morse Magneto FM-X4B7A