Wore black AND white belts with both uniforms.
Changed images to all white belts and added disclaimer that 'black belts also worn'
Wore red belts with white pants.
Wore white belts with red pants.
This photo is from a Browns-Bears preseason game on 9-01-50. It looks like orange pants to me.
By the way, I really enjoy your site. I have written Browns history books and have done my own research on the history of their uniform. Your Browns illustrations are very accurate, although there are a few subtle striping revisions that could be made.
I'm buying this photo for use in a book.