welcome to the site! As Frank said, 6400 is a 2 ton. Brake return springs may be fun to find. I called brake and clutch in Seattle and got a part # for my 1958 6400. They are no longer made but, I was able to find some NOS springs online using the part # they gave me. I would start by posting in Big Bolts forum and see if someone has a part $ for you and then go from there. As mentioned, you may want to post in parts wanted if you don't get any help with part # in big bolts.
Just don't start a parts wanted thread in a forum other than parts wanted. It will get moved. (ok to ask for a part # or help on where to source parts though).
