Steve,
I also have a 53. Some of these guys that have owned multiple trucks may have seen a solid piece of material back there. But, when I took my speaker grill off to paint, there was only a metal mesh piece back there. The mesh holes are small round holes. It had either lost most of its paint. Or, it just got some light overspray from the factory painting the outside of the speaker grill. I media blasted it several years ago and painted it black. It looks nice behind the speaker grill. You can see it, but you have to really get at the right angle to see through it. I chose to install the old, original radio back into the truck. There is no light that comes up from behind it. It you are not planning to install a radio, I would imagine you get a little light from behind the dash. Not much, but a little. I have not seen that piece of mesh in any of the reproduction catalogs. I suppose somebody on the swap meet page may be selling one. Or, look on line at the auction sites. Hope this helps. Good luck with your restoration.
Rugo
