Schwinn stamp on handlebar center post war - need date info

Anyone have any info or insight as to when Schwinn began stamping the center of their handlebars. I have a handlebar for a ballooner bike that has "Schwinn" in the center.

I know the later bikes, such as the 1970s Schwinns, had "Schwinn" plus a catalogue code along with a date code.

The info I'm looking for is dating bars with "Schwinn" stamped only.

Thanks

If my memory isn't shot, I believe it was 1966 for the Schwinn stamping on the bars.

If it's a cross bar that's repop