66 dart convertible

Your work is awesome. I was looking at your radio bezels, I'm going to have my dash refinished and my bezel has been gnawed on to fit an afte market radio. I'm looking for one but I have a square hole in the top left corner and see that yours don't? Any idea what that's for? I got the car as a basket case and don't have any before pictures. By the way, great information in this thread. Thank you!