Darin, welcome to the 'bolt board!
My great-uncle had a Mobile filling station that started out as an Esso. He even named his dog "Esso"
For some reason he changed over to Mobile, and became a distributor for them. He had a '47, second series, bob tail tanker, with the cab painted black & the the tank painted the Mobile red. He also had a '49 GMC tanker that was painted a kind of orangish red. I don't know, but it seems like back then, they didn't have to stick to company colors that much, as long as the name was right.
One other thing I remember about his trucks, was that both of 'em had the stub of a "King Edward" cigar in the ashtrays
