[weegee]

I've seen the Adams gums in stores on occasion. This website mentions that they are periodically rereleased to the market:

Black Jack Chewing Gum (fan page)

I don't know how well a box of gum "keeps" sitting on the shelf.

[Still Thinking]

I've seen them, too, and I make sure to buy them whenever they come around, but it's only the BlackJack/Beemans/Clove flavors. I've not seen the sour fruit flavors, which I actually liked even better.