AC Center Vent Hole Size

[Jasons65]

I'm picking up an original ac cab for my truck but the cab has been gutted of all the original pieces. I'm going to go with a vintage air ac kit so I'm trying to figure out what to do with the hole. I was curious if I could get the dimensions to see how close it is to fitting a stereo in the hole or if I'm going to just find an ash tray to put back in that location. Any help is greatly appreciated.