OPGI sells a rocker molding clip for the 66 GTO which fits 66 98's.

Thanks GM interchange!👍

OPGI Part # G221257 is a perfect replacement for 66 Olds 98 trunk rocker molding clips. 1-562-594-1000. OPGI lists as GTO Rocker molding clip.

Be sure to buy one or two copies of their bathtub molding clip installation tool. The clips are nearly impossible to secure tightly without it. I broke mine from twisting after 3 of 8 clips.

I'm not associated with OPGI, just wanted to let you all know.