The 1967-68 cap sets were one of the first MLB Players Association-licensed products available nation-wide. Coke blacked out hats to save team license fees, knowing that player images help move food and perishable products. (By comparison, team logos sell better for caps, shirts, and clothing.)
On the 3rd of July, 1966, Braves pitcher Tony Cloninger hit a pair of grand slams off San Francisco pitching and remains the only pitcher to do so in MLB history.
Tony hit his first-inning slam off Bob Priddy, already pitching in relief of starter Joe Gibbon.
Ray Sadecki mopped up the last six innings of San Francisco's 17-3 loss and gave up Tony's second blast in the 4th.
Cloninger finished with 3 hits and 9 RBI, a monster game for anyone, pitcher or slugging outfielder. (Hank Aaron hit "just" a solo shot and probably bought the post-game beers.) Might a guy hit three grand slams one day? If so, it probably won't be a pitcher, making Tony's place in history pretty secure.
Read more about Tony's post-playing career and life in retirement at this retrospective article from DenverNCNews.com.
UPDATE: Some crowns include Tony's position (P) on the right edge. This might distinguish those produced in 1967 and 1968, but I haven't seen enough to know for sure.
Value: Low-grade Coke caps go for $1 or less. HOFers or commons without edge wear and rust cost a little more. (eBay sellers often ask $10 or more, several times what they sell for at shows.)
Fakes / reprints: It'd be hard to fake a Coke cap profitably and I haven't seen any in the marketplace.