GPL

Hi there, I just came into possession of a Marks Brothers western saddle. It seems to be all original and I have a letter from my friends family as to it's lifelong owner. It is such a beautiful piece of history as well as art work. I'd love to know if I could find out more about the saddle. The only marks on it are the makers mark and the numbers 555 on a tag located on the left side. Anyone have suggestions? Thanks for any advice.