I have both (a couple from the 1940's, and one from 1967), and to me, with your eyes closed, there is no difference. The post 64 have a lifter that looks much cheaper, and some other cheaper parts that are less obvious. They also don't hold up to rebluing, which make Krylon a popular substitute in my parts. My thought is that there is a big difference to the trained eye, very little in function.