It's a 55. After 55 they just used one number for the date code. IE: A126 = Jan 12 1956. Anaheim Gear here in So Cal was rebuilding syncros a couple of years ago so they may have some parts. But, from what I see and what you have indicated about the condition, put it back together and use it. The cage is one wear area, also check the roller clutch cam for divots on the contact surfaces. This OD trans was used through 1965. Solenoids, governors, and many internal BW components were common to Fords, Ramblers, Studebakers, and others. It's not unusual to find mix & match parts.
Fred
