This style Kodak back started in the 50s (probably late 50s). And kinda became the generic postcard back used by postcard printers thereon after, very commonly in the 70s and 80s. So it's very hard to tell dates on them generally. Just based on numbers the answer for most is the 70s or 80s. But I've seen a few 50s ones.
This I am not sure. Really the only clue to date them is age wear and smell. If it's perfectly white, no smell at all and sharp all around it is almost definitely 80s.
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