Sterling Gasoline Sign

This old, double sided, porcelain sign was part of my childhood. Little did I know back then that I’d one day have it. When I was a kid, our “sandbox” was a big tractor tire filled with sand. That was 48 years ago, and the sandbox was there before I was born. This sign was put in the bottom of the sandbox to keep weeds and grass from growing up through. After all us kids, ...with me being the youngest, were too big to play in the sandbox anymore, my parents got rid of it but kept this sign all these years, first in the barn and then in their shed after the barn was torn down. They knew I like old signs, so it now belongs to me. It measures 42 inches in diameter, and despite being buried under sand for who knows how many years, I think it’s in great condition. The other side of it is actually in better condition, but there’s something all over it that’ll require a lot of scrubbing/cleaning. There are no mounting holes at the top, but there are two at the bottom so I’m assuming this sign had a stand and was sat outside the gas station. It will take its place of honor in my garage. I've never seen another one like this, including on eBay. I've seen smaller ones that were on the gas pumps but not a big one like this. Does anyone have any information about it? Year? Thanks!