Duster Rear Window Louvers
Here is a link to what I put on my Challenger. It is a made in America product. When I was installing it I had some questions and was able to speak directly to whom I believe was the owner. He was very helpful. I don't know, maybe with some interest they would fab up a mold for A-bodies. I haven't done any measuring, but a guy might even be able to convert one of these.
http://www.carid.com/2008-dodge-challenger-deflectors/eg-classics-deflectors-326870.html