i have a bunch of transformers and they have the dates like i have optimus prime it says takara hasbro 1980-1982 and all the other toys say hasbro or takara! and most are made from 1982 -1985 also i have jet fire but the stamp doesn't say hasbro or takara but it does say bandai 1984!
i'll answer throughly. bandai is a japanese brand which produce toys. but you asked how do i tell if my transformers are G1 or real. you can tell by its looks. g1 models looks like a box (quite square in shape), but the latest 1 looks modern.
this is defined in the action picture, which occurs between Season 2 and Season 3. additionally, word that new characters ensue in particularly some episodes devoid of rationalization, and not in easy terms in Season 3.