1st Gen Barracuda ?

caferacerx said
some of the 66's also had the Valiant emblem on the back not sure if it was early cars or /6 cars also 64 65 had round center tail lights 66 had square center tail lights and shark fin turn signal indicators on the front of the fenders

If you seen a Valiant emblem on a 66, then someone installed it.

The Valiant emblem was a 64 only thing. Barracuda was an option in the Valiant line up in 64 but became it's own line in 65.