We all know that AMC never made a plastic part themselves if they could buy from someone else. I have to think the center A/C vents must have come from Ford or GM. At the moment, I'm thinking they look similar to Chevy truck vents of that era. Does anyone know if there's a direct fit from GM or Ford? I've tried searching this topic, but came up with nothing...I might be doing it wrong. :)
For something like this, I'd guess that AMC made them. I'm not 10% sure though. Remember that the Spirits and Concords were the same platform as the Eagle, so some years from those might work as well.