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heres 1978 D44 front shield on the hub, sorry about the snow
The only differecne that I know of is that the axles in half ton would have smaller brakes for 15 inch wheels, but i dont know if that means the whole thing is smaller and the rotor is, or if the thickness of the rotor/hub is different and the caliper is the same with minor change in piston or something.
Remember, 1/2 ton and 3/4 ton are nominally the same in many ways in these trucks, just springs/brakes/axles (Capacity) , so ratios and tires and wheels not necessarily the axle itself (except 14 bolt semi floats and 10 bolts rears would be locked to one or the other, or 14 b ff)