My RPO codes: MM4: Transmission, Manual, 4-Speed (Merchandising Option); M20: Transmission, Manual, 4-Speed (Muncie).
The transmission in the truck is a 5-speed; first gear does not feel nor sound like granny gear. My reference is the SM420 in my last truck (1966 C10) - first gear was a crawler (7.05:1). I don’t see any part or model number on the transmission case, which is aluminum. Do these photos provide any identity clues?
The transmission in the truck is a 5-speed; first gear does not feel nor sound like granny gear. My reference is the SM420 in my last truck (1966 C10) - first gear was a crawler (7.05:1). I don’t see any part or model number on the transmission case, which is aluminum. Do these photos provide any identity clues?