Hi I bought this sign off a 91 year old guy today who worked for quAker state as a delivery guy then tearing out stations in 60s. He said he kept it because it was the only one in over 300 stations he ever saw. Measures 46 inches wide by 4 feet high porcelain single sided and I would classify it as near mint to mint. Green stuff in photo is coming off was stored inside for last 50 years. I talked to a few major collectors and no one has ever seen one like it. Any idea of era like early forties? And value would be appreciated