The peghead shape and color is an interesting story by itself.
Most prewar and wartime Gibson banjos are actually marked with factory order numbers rather than serial numbers, but for right now you don't need to be worried about the distinction unless you're just especially interested!
If your banjo has a wooden back, or resonator, you'll need to remove it to get to the factory order number.
Welcome to The Banjo Philes, a website for the Twang-Tone-obsessed.
In this space I share what I have learned about my favorite subject..... Like so many others, I am fascinated by that illusive Gibson Mastertone sound that is associated with the rare pre-WWII flathead Mastertone banjos.
Here are some more pics: The Gibson Mastertones of the 1950's were constructed with about the same specifications and quality levels of the 1930's and 1940's.