Looking for info on this single sided porcelain Shell Motor Oil sign. It was obviously made in 2 pieces and does have holes in it. I'd like to know how it was originally displayed or used in advertising. I'm wanting to hang it on the outside of a shop with a light shining on it. When it's together it's about 6 foot. I did have one collector tell me that he thinks it was a highway display / billboard and had a frame built around it, and it's from the 1920's. Thanks for any info.