Factory window shades

I have a '65 Galaxie that has a new in 38 year old box window shades. Even had to remove the blue protective layer off when I removed them from the
box. Anyhow, how do I install them? I know the slide in to the top of the window but are the tabs supposed to be bent somehow or what? They are somewhat loose and pop back out pretty easy. I know they would be gone at highway speeds. Any advise would be greatly appreciated from anyone whom has dealt with these first hand. THANKS!!
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