Several years ago I copied what another guy had done and put a set of Mopar disk brakes on a '55.2 GMC 3/4 ton set up for duals. The major problem with it was that the steering stop tab on the steering arms has to be removed for clearance. This then means that another way of limiting steering travel has to be made. Solid axle ('53-'62) Corvettes have a heavy bracket under the steering gear that limits the pitman arm swing and something similar needs to be built.
A '56 GMC 1-ton followed me home a while back and I decided to keep it all GM this time. I ended up using mid-80's GM 3/4 ton 4 wheel drive front rotors and calipers. After a number of "measure - draw - cut" cycles using 3/8" plywood to mock up and verify, I had the brackets cut out of 3/8 steel plate this week and I assembled everything on the axle yesterday and it looks like it will work.
Do it yourself disk brake kit. Unless you have your own lathe or access to one, the simple looking spacers should be painted green for what it costs to have a machine shop make them.
Next step is to weld the lower tabs to the basic plate, clean & paint everything, have the kingpins fitted and put everything back together. I have a set of roller wheel bearings for this so everything should be ship shape.
