The change over from Huck style brakes to Bendix changed the backing plates. There is a change to the torque tube diameter as well. The brake drums are a lot cheaper for the Bendix style, and the whole thing is a bolt in change. A lot of the 1950 types are worn( a lot) so axles and seals get to be an issue. You cannot just change the drums, and brake parts. It may be worth finding a complete unit to replace the older one. Or you can take the time and dollars to fix the one you have. Check the parts for sale section, and keep looking for one removed from a Hot-Rod guy. Some options but no parts swapping from early to later with this unit.

Steve H