Yes, as a matter of fact it WAS a non-AC car. Oops! I knew that , but didn't figure it'd make much difference. Guess I was wrong on THAT count! I didn't think the difference would be great enough to matter. Is there a duct for the center A/C outlet that is causing the problem? Not really having much radio install experience in a Gremlin or Hornet, I will have to look at my '78 GT, it has no radio in the dash currently. Hmm. Sorry I might have mislead ya! Wasn't my intention, Daniel. I'll try to give better details in the future. I also have several stock AM/FM radios , I'll measure them to see how deep they are. How deep is this Optima, from faceplate to rear edge? Jerry