I guess I was incorrect in my thought that those letters and numbers were supposed to start with one letter, then the date code and the last letters would identify what vehicle it came in.
You might be thinking about the chassis serial number which are in a different format than the engine serial number/code...your 1940 1/2 ton chassis number would look something like this,
5KC04 12345
Number/s = Plant (5 = Kansas City)
Letter = Year/Model (KC = 1940 1/2 ton)
Numbers or letters = Month (04 = April), Note, some years used letters to ID the month.
12345 = unit number normally starting with 1001
Mike B
