Your stock shifter has nothing to do with the gear indicator. Its not even connected directly to it. The shift lever on the trans is connected to the rods to the column where the indicator is. I'm not sure what parts are worn out in there but I believe its the spring in the dash for the indicator thats causing your problem. Also, I have a B&M Pro-Stick installed in the factory location.
84 Monte SS stolen September 2012. 077 DFE Jefferson County KY plate. $2500 reward. Vortec headed 350ci, th350, 3:73 limited slip cast aluminum cover, Autometer gauges, Pro-Stick, 2.5" fiberglass hood.