I don't recall if I've ever seen a discussion breaking down proper timing for hollow versus T shaped mast jacks. I wonder if it might be a situation where they used 2 different suppliers and both were used concurrently?
Another jack related item I've never even seen discussed is that some components are occasionally seen painted dark green instead of gray. I've seen the hook and maybe the base painted green on some '71s. Including my friends June built '71 Challenger convertible that he has owned since '73 so very likely the original jack.