mainshaft
#1
#2
Just a note, when you put the 5th gear on, it's gotta be snug on the splines, and then the upgraded nut usually works well (with lots of permanent strength loctite), However, if the splines are loose and the shaft doesn't properly support the gear, nothing will work well for long. As to how hard the the shaft is to replace, I'm not quite sure... if you do it before me, let me know.