This is what the original plate set looks like for the 1947-55 1st Series AD without the Air-Flow heater installed. The small round plate installs in the engine bay on the firewall.
https://www.flickr.com/photos/advance-design_parts_co/15838946822/in/set-72157631868452754
https://www.flickr.com/photos/advance-design_parts_co/8129182431/in/set-72157631867396207