Has anyone heard of Aero Service cards? Here is a link to an ebay auction that just ended for a Joe Garagiola:
https://www.ebay.com/itm/405277759657. (I was the very disappointed and frustrated underbidder). The card looks identical to a 1949 Schumacher Service Station card, but the back has an ad for Aero Service rather than Schumacher.
I wonder if the Aero and Schumacher cards were made by a single publisher, who marketed them to service stations with customized advertising on the back. Kind of like Felix Mendelsohn's M101-4/5 cards or 1970s MSA discs. Could there be a third back in addition to Aero and Schumacher?