Not sure why you call it a Mystery shifter then. OEM 68-71 were Hurst shifters bayonet style that the handle slips and locks into the rectangular socket. All my original 64-65 A body shifters say Hurst Competition Plus. No stop bolts. I have had probably 10 of them over the years. Aftermarket A Body Competition Plus shifters have a welded handle with stop bolts and the shift arms have larger holes for bushings and slightly different shift rods and use the earlier Hurst mounting plate. If you want to rebuild your OEM Hurst shifter use Competition Plus parts. They all work. Anyone curious can go to the Brewers Performance website and click on the "before you order" tab to get an ID aid for 4 speeds and shifters.
