Need Help decoding an early tail # format

[L-4Pilot]

We have been unable to interpret the format and content of the tail number painted on this O-58A, photo taken at Post Army Airfield in early 1942.

We know it is not the standard Radio call # which came in to use at a later date. We believe it could contain Airfield, Unit and or aircraft number, or guess # two manufacturing data that was painted on Aeronca L-3s that contained portions of serial #, construction date, and engine serial #.

A normal and later radio call number would read 2-7796 for example.

The military serial # range on O-58A aircraft was 42-7793 to 427812 . Thanks for your help.

[L-4Pilot]

One suggestion we received is Aircraft # 20 and the unit designation is 158. The unit appears to have been operating with a mixture of aircraft types similar to the 109th at that early stage of the war. Don't know what unit 158 would have been.


Here is aircraft # 12 with the 220th Observation Squadron. The numbers 12 and 220 are painted on the vertical fin and also in black on top of the left wing.