PLEASE HELP! '64 emblems on '65 GT!

I appreciate the info and I certainly see a pattern of most being on 270's, but there are two '65 GT's (my brother's car being 1) in the pictures above as well as a 170. Also, I have seen several '64 GT's with this emblem on my google and yahoo image searches. I find it very improbable that these emblems were added to all these cars after the fact. They are all in the exact same location. I also find it interesting that both of the '65 GT's are convertibles (and thus don't have the sail panel GT emblem). Maybe someone on the LA assembly line decided the car looked to bare with no GT emblem?