Joe58 - Which parts typically needed replaced?
Common problems I have seen are missing gate spring and hat shaped retainer and problem with reverse detent plunger.
If it was an early take off shifter, the rest of the shifter may be in good shape needing just a good cleaning and grease.
here is a picture of the gate spring and hat shaped retainer and parts of the reverse detent plunger with 6 balls and a ring shaped spring. The plastic dust cover for the reverse detent is missing in this picture
The Muncie shifter just was not designed for banging gears like a Super Stock National Champion. I think the gate springs would just pop out under hard use.
The reverse detent plunger would fail from dirt and lack of lubrication.