These are from approximately the 60s.
Back of pictures coded 128B
“Kodak paper”
Picture size inches 3 1/2 by 3 1/2
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Sign up to join this communityThese are from approximately the 60s.
Back of pictures coded 128B
“Kodak paper”
Picture size inches 3 1/2 by 3 1/2
Kodak papers marked on the back with A KODAK® PAPER are from 1961-1972. After that the mark became:
THIS PAPER MANUFACTURED BY KODAK
until the early 1990s. This isn't much, but it sounds like your guess about the 60s is pretty good, though they could also be from the early 1970s. The "128B" is a mystery--someone else may have encountered that, but I have not. In my experience (and I've done a lot of this), the image content itself is going to be key to getting a more precise date range.