I live in a very small town and have a hard time finding parts for my 68 overlander. I need the same brake backing plate, and no where around here has anything. Would like to find were to find new brakes.
You will likely have to order them via mail or the internet unless you have and RV dealer close by. The backing plates are either Kelsy Hayes or Dexter. You can google them and find a local distributor or you can go to Vintage Trailer Supply or any of a dozen other dealers that have a website to order them. They weight quite a bit so be prepared to pay freight above the $50 to $80 price per wheel. Take the meaurements of the inside of the brake drum diameter and brake width so you get the right size.