I want to search for a replacement for the OEM Stereo Dash “Dummy” Insert that was removed when my stereo was installed. I can’t think of how to ask the question in a search engine and find an answer. Certainly someone here who installs stereos will know its ‘proper’ name.
If your car isn’t too old you could ask at stereo shops. They probably would just toss those away. But I think there haven’t been cars sold without some sort of stereo for quite a while now, so you might try Ebay, too. I just looked using radio block off plate and found a bunch, including one for a 1950 Hudson for @25. So, they are out there.