OK, I know you're kidding about the 'Bird wing. I have never seen anyone ever able to pull it off on any vehicle and make it look like anything other than an abortion. That having been said, I don't think it'd be impossible to come up with some fresh design.
You may recall that I'd once said I had a desire to install a whale tail on the back of a Camaro I once owned. I've never seen one on a Barracuda but it might be interesting. - And hey, in a twisted way it would fit into the whole fish theme of these cars. View attachment AF12_r523_01.jpg
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It might be a horrible idea but I wouldn't rule it out too quick. The whale tails weren't very common even back in the day. Most people wouldn't recognize them nowadays. I like the idea of thinking 'out of the box', adding 'old school' touches, and trying things that aren't cookie cutter copies of every other vehicle out there.Who knows? They might look really cool on a fastback 'Cuda. The Camaro did have a swooping roof line too.