Dual piston 8,100 lb disc brakes or backing plates only 69to?

[SoCal250]

Here's what I'm looking for the backing plates only or the calipers and rotors if in good usable cond of course .

I'm sure these were used on other than the 8,100lb front end they have a single piston as well although the square bolt pattern is what I need since the 69-72 were identical to the drum brakes this way I can use my 69 spindles.