Do you have this emblem on your 66 fish?

it appears from that pic,they used the valiant emblem in a baracuda center grille,,the valiant center grille uses a valiant emblem but not with the big bezel around it,, that same bezel is on the fish emblem,,,so i would say you could convert it to the fish emblem with out switching to the valiant center grille,, the 2 center grilles look that same unless you compare them side by side with the emblems off,,,

the rear window trim,,64/65 used the valiant emblem in the center,, the 66 used the fish,, but appears yours is either an early model,,or maybe a canadian model,,,,im guessing a early production,,

the 1964 barraacuda early production had a valiant script on the right side just under the trunk lid,, the 1964 65 66 barracudas are based off the valiant as you can see,,,finding another valiant grile emblem like yours may be very hard,,,