[theastronaut]

I took the transmission off the engine and cleaned it, then tore it apart today to figure out why it wouldn't shift into reverse. It ended up being a super simple fix; someone had pulled the reverse light switch off and left the sealing washer off. That let the switch sit in the case too deeply and the spot on the internal shift linkage that swings over to press the detent ball was hitting the tip of the threads, stopping the shift linkage before it dropped into reverse. Unfortunately I didn't spot that until I had the 5th/Reverse gear stack off and the case apart. Getting the shift fork alignment and 5/R gear stack back together correctly was a chore since I didn't have a clue about what I was doing (never been inside a transmission before). It's all back together (and working!) now except for torquing the lock nuts on the end of the shafts and installing the end cap.