Deciphering an L-4's Army Air Core Serial Number

[Speeddemon651]

I was wondering if anyone know the cypher for figuring out an L-4's piper serial number from the given Air Core's serial number.

For example - 44-80782 is a 1944 L-4 but what do you have to subtract to get it's serial number ?

 

[FreddyK]

 

[Speeddemon651]

 

[AOP]

 

[43-491]

 

[43-29080]