Need Help in Tail # identification...unknown format

[FlaL4]

Does anyone know what these tail numbers represent in this photo. The photo was taken at Post Field in early 1942. Tom Lee and I have been looking in to it and are stumped., They are not the radio call numbers (serial #) that became prevalent after June 1943.

We believe they are either.

1. The numbers contain portions of USAAF serial #, construction date, Aeronca serial # and Engine serial #
2. Identifiers for the Airfield and an assigned aircraft #.

Thanks
Steve

 

[FlaL4]

 

[high time cub]

 

[AOP]