The first GM 4x4s with disk brakes used a rotor attached to the hub. This was done on the 1/2 and 3/4 ton trucks. The conversion for 3/4 ton trucks would be the same as that used by the aftermarket vendors for their 6-lug disk conversions.
That is if someone wanted to use their stock hub and bearings. The only thing wrong with the stock ball bearings is the cost compared to timken type bearings.
