Gas cap confusion

Slant6dan sold an awesome gas cap a few years ago I have on my 66’ with 0issues.
It’s not locking. But the best cap I’ve ever owned.

I’m not sure on the locking style. Before the rebuild mine would puke gas out toward the top, hot days, just sitting there. I installed a vent / roll over valve at the top of the tank and followed the info on this site - using the search feature at the top of the page is your best friend.
Plenty of people here have already laid out the styles of caps and uses you can search and understand what you have and what you need to do. I don’t want to quote their work. Good luck!
Syleng1