See-Threepio was released in 1978.
See-Threepio (C-3PO) shipped on all cards from the STAR WARS 12 back to the The Empire Strikes Back 41 back. It overlapped its replacement C-3PO (With Removable Limbs) on The Empire Strikes Back 47 and 48 back card. This figure first appeared on the Star Wars 12 back card.
Though all vintage figures have minor variations, the only major variation is the hard to come by Japanese Takara version, which, though in a similar stance, is an entirely different sculpt. It is easiest to spot by looking at the arms and especially the head.