Working on my 67 HO GTO automatic, and trying to put it back as "correct" as I can afford. Automatic cars originally came with exhaust resonators. I've called all over the place, and Gardner exhaust is about the only people that seem to have them. However, you can't buy them from Gardner unless you buy a complete $1000+ exhaust system. Y'all seen them anywhere for sale? If they are not out there, at some point I might have to find an original car with resonators and see if I can reproduce a set myself.