View of workers rustproofing spare parts at Plant 4, Service Dept., Bldg. 20, Operations Civilian and Military, GMC Truck & Coach plant. Printed on front: "GMC Truck & Coach Division." Handwritten on back: "Plant 4, Service Dept., Bldg. 20, Operations Civilian and Military. Rustproofing spare parts, first floor. Factories--GMC, ca. 1943."