Classic Industries offers a wide selection of Emission Control Components for your 1974 GMC Truck. Classic Industries offers 1974 GMC Truck Catalytic Converters, 1974 GMC Truck Check Valves, 1974 GMC Truck EGR Valves, 1974 GMC Truck Emissions Sensors, 1974 GMC Truck Hardware, 1974 GMC Truck Hoses & Clamps, 1974 GMC Truck Mass Air Flow Sensor, 1974 GMC Truck Pulleys, 1974 GMC Truck Smog Pumps & Components, and 1974 GMC Truck Vapor & Charcoal Parts.