Yes, it is the same stick. It is NOT removeable. Same as Matthons. My guess is that Hurst sold them until about '75 or so. Then Mr. Gasket sold them for a couple years after that.
This is pure speculation, but I am guessing there was little to no market for A-body Hurst Competition plus shifters. After the factory shifters started to pile up in junkyards, Hurst quit making the specific replacement pieces. All factory cars had them except for those 2 1/2 years, and people just got a nice one out of a junkyard for their car when they trashed the inland. Back in the day, I saw A-body cars in junkyards with the sticks still in them rusting away. No demand.
