Here is the deal, I have a Muncie M-20 rebuilt w/ new Hurst shifter. The transmission shifts fine but in 1st gear when not under power the shifter and transmission will drop in to neutral for no reason. I belive I have the shifter adjusted and the stops set correctly. All other gears work fine. Any thoughts?

Welcome to the site.

Sounds like the shifter is still just slightly out of correct adjustment. Might want to pursue that a little more. Its either that or combination of things. The dogs might be worn, the energizer springs might need to be adjusted, the sliders are worn out or the side cover spring might need to be changed to the "Double D" spring to retain the gear selection.

Its most likely just an adjustment, as you can have problems......and they will adjust out in a half turn of the rod.

Might be the adjustment but I would put money on the synchronizer slider being worn and/or the clutch teeth on the first gear are worn. I had the same issue years ago and it was obvious what was causing it when I got the tranny apart.

Who did the rebuild?

-Mark.

I have had the trany for years and it had always worked fine. I took it in to be freshened up and gaskets replaced by a shop here in Denver, They said all was fine with the exception of a bearing and 2 synchronizers. Anyway I will look at the adjustment again but if I cna't get it right, I'll have to pull it and have it looked at again.