I installed a regular shifter from a regular 2.66 low gear cast iron transmission from a 69 Barracuda; onto an F-body overdrive. Beside flipping the lever, There was no drama.
At some later date, I installed the regular 2.66 gear train into the alloy box of the F-trans, and still no drama. I even installed the alloy tail , still no drama.
At some later date I installed an old 70s Mr. Gasket Bang! Shifter; still no drama.
At some later date, I installed a Passon Performance alloy box.
What I'm saying is that in my case, everything worked with everything else, so IDK what could be different.
Oh wait, I seem to remember nylon isolators on some factory F-body external levers; I didn't have those. Maybe that's it.
