Like I said, they are different! The early D60 ford axles used different brakes and therefore they need a different disc brake setup for the newer ones. These are for the years '77 & up to when the Sterling started being used.
They are just like all of our Disc Brake Brackets in that they are 3/8" thick! They use the '75 Chevy 3/4 Ton 4x4 Front Rotors & Calipers but you may have to remove 1/10" of the inside diameter of the throat of the rotor. It was the best choice of Rotor and any brake shop should be able to do it for $20.
NAPA Part numbers for '73-'87 3/4 Ton Front, 4x4, Chevy Calipers and Rotors:
Caliper ONLY: LH - N4674, RH - N4673 - Both of these are LATER year part numbers
LH - N4597, RH - N4596 - Both of these are EARLIER year part numbers
Rotor Only - 4885677 - all years