for 67 fast back experts (window trim)

It's not original. Period. It's something a lot of people have done as a mod, going back 50 years, because that plastic lockstrip didn't last 5 years in the sun. Back when the stainless was still available from the dealer, it would be a no-brainer to replace the trim any time you had to replace glass. If he pulled the glass to replace it with tinted glass, well, there you go... It's possible the dealer who replaced the glass just did the trim automatically, because he knew the customer would otherwise complain when it didn't last. So the trim wouldn't show up as a specific item in the old owner's receipts.