That 4200 lb. weight given in the shop manual load capacity chart is the gross vehicle weight rating (GVWR), not the empty curb weight, of the base truck with base tires. The actual GVWR (up to 4600 lbs.) depends on the tires used, as shown in the chart. Curb weight would be in the 3325-3385 lbs. range, according to Chevy specs, for the 1/2 ton AD's, not including any optional equipment.
