I have a 1967 coupe barracuda with a low serial number and shipped march 1966.

Oh very well could be. Back then the design teams were a few years ahead of production. They had to be. It could be a prototype or a pilot car.
Perhaps, but prototype cars would not have been built on the regular assembly line and as such would not have a fender tag, VIN,build sheet,,,hence its is really hard to prove a pedigree on those.