Since the Competition Plus line of shifters was only aftermarket over the counter there were generic and specific mounts, rods, and linkage per application and year.
They were not just over the counter. Z/28 and all 69 four speeds had them.
No Actually the Competition Plus is a retail line. Hurst made custom shifters to OEM specs for Factory installation only, for GM, and others in the late 60's early 70's that are not Comp Plus line shifters. These special shifters were available as service replacement from GM parts counters but not sold as retail units. The competition plus line was sold retail and marketed for the same vehicles that they manufactured special factory OEM units for. So in effect you could order a sag trans and get a muncie shifter from the factory, but buy a Comp Plus shifter down the corner at ACME and have a much better shifter.
While they may all "look" the same they are not. The Comp plus line had adjustment bolts front and back and other features such as push down to reverse lock out. Factory OEM Hurst shifters do not. The linkage, rods, sticks and mounting plates are not interchangeable between the two lines for the most part. While you may get a rod or two or a lever or two to work, the factory stuff works best with factory OEM Hurst shifters, and aftermarket over the counter works best on them. Mixing an matching the parts causes misery - been there done that. I spent hours researching archives. There should be a few decent links here and at TC documenting the difference.