David M

Parts for the later NP420 transmission (1956-) seem to be easier to find than the early version. I can find synchro rings (inner and outer) for the later version (1669891 and 1669893), but not for the early. They certainly look identical to the casual observer though. Does anyone know if they would work?

Wow, that is really helpful. I have the shop manual for the truck, but not a parts manual. This is great info. I know the tranny tech mentioned broken pins, but I'll take this info to him and see if I can narrow down what I need. Thank you for taking the time to look it up!

Thank you, Dodgeb4ya. I'll check there. Dennis Maroudas tells me I'm looking for synchro assembly AWT262-2.5 The casting has date 1/6/55 (or maybe 7/6/55, it's not super clear). The top cover date is 1/31/55.

I've got a 1955 Dodge C-1-B6 with a NP420 4-speed. The guy who sold it to my Dad (in 1973!) said it was late in the model year and maybe got some '56 parts, but who knows. In any case, it's got a casting number C-88221 with a top cover C89988. The pictures below are from another post, but mine looks the same, with e-brake and all. (Not sure about the tower though.) It's being rebuilt, but the synchronizer is blown and I can't find a replacement. Any ideas? I've asked D. Cirillo and Vintage Power Wagons, no luck.