Well, it appeared at launch in 1956, but it stopped being produced in about 1971, afaik, when the SL pedals appeared. There were probably lots of tabbed pedals around in inventories, though, and it's not like they recalled them, so they could still have been sold for quite some time after that point.

Is everyone aware that there are two versions of the black SL pedals? The flip tab and quill 'points' were made less pointy, probably during all of the CPSC nonsense in 1977-1978. There were also short-lived silver-cage SL pedals, afaik, but I've never seen any.