As kb3cw stated, it's going to be out of the 4000, or 6000 series lineup. 4000 being 1 1/2 ton, 6000 being 2 ton. Check to see what the ID plate says, in the driver door jamb. 3100 series is a 1/2 ton pickup, 3600 serries is a 3/4 ton.
Spanky Hardy Collector Of Fine Old G.M. COE Trucks & Antique Holmes Wreckers
