Thanks for all the replies (and guesses ) but I believe Keith has pinned it down!
I didn't mention before, but the closing retail store was a Kmart (where I worked part time for 2 years) so I didn't think the tool would have been use for anything relating to the operation of the store....
.....In the early to mid '80's the store did have a Car Care Center that did oil changes, shocks, tires, etc. but I don't believe they messed with any window moulding gaskets(?) ......but you never know!!!
p.s. - Come to think about it....in the early '80's, the sliding back glasses for pick-ups were pretty popular and a lot of garages did install them (I've installed several but I used a heavy cord soaked in WD40 around the gasket) and I know that Kmart sold the back glasses.....Hmmmmmm, maybe they installed them too, and the tool was use to help out with stubborn gaskets (?)
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Women are like phones. They love to be held and talked to, but if you press the wrong buttons you'll get disconnected!
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Life is one fool thing after another whereas love is two fool things after each other