help a brother get a brake

[nu2-72]

pun intended.
1972 3/4 ton 4x4, front axle brake setup. This is todays issue.
The calipers for 1/2 and 3/4 are the same.
The rotors are not.
Knowing several things, I need some help.
The backing plates with dust shields are almost non-existant. And because the trucks are different, you cannot interchange them.
I went to a local salvage yard and asked for later model 3/4 backing plates. They had to pull them and I picked them up. He assured me that they were 3/4 ton plates. They cannot be. The rotors dwarf the plates and it would be impossible to get the caliper mounting bolts installed.
Does anyone have a 73-up parts manual that might look up the backing plate numbers for me?
I will take these back and see what he says. Maybe I need 1 ton in 1973-up.