1981-83 chevrolet 3/4 ton rear brakes?

[1946rustbucket]

I'm looking for the rear brakes off of a 1981-83 Chevrolet 13 inch rear drum brakes on a 3/4 ton truck or suburban with a semi floating rear end. Here are pictures of the drums and backing plates that I'm looking for. They are mounted on a 1952 Chevrolet 3/4 ton full floating rear axle. I'm going to use them to convert the rear brakes on my 1946 Chevrolet 3/4 ton. What are the part numbers for the brake backing plates for a 1981-1983 Chevrolet 3/4 ton with a semi floating rear axle with 13 in drums?