ive heard it talked about a few times but cant find anything on it. what it do and stuff like that?
i feel like its something dumb that i should know

 

Its pretty much nothing really A truck with alot of miles or some performance behind it. The 5th gear tends to start backing off the shaft and causing the gear to come off the shaft, and you will have no 5th gear. Theres 2 things you can do to fix this little problem. Buy a new mainshaft or just tack weld the 5th gear nut on.Everyone ive talked too that has welded it on. don't have any issue with it. Just make sure you dont taper the shaft. If you need some pics of it, i got a few of it

 

ok i was thinking it was to change something on the 5th gear cause the top speed is pretty low but i still have 5th gear so when i put a new clutch in soon ill take care of that.

 

That would be the best time to do it!!