M - 42 Duster The self - propelled M42 Duster , sweeper , is a version of the American light tank M41 Walker Bulldog , turret armed with two 40mm cannons Bofors manufactured under license . Description . The M42 Duster series is based on the M41 " Walker Bulldog " chassis by fitting the twin gun mount inside the hull turret ring . Three models were standardized , M42 produced from 1951 - 1953 , the M42A1 standardized in 1956 , and M42A2 , all with the nomenclature " Carriage , Self - propelled , Anti - aircraft , Twin 40mm , 25 - ton , ( Duster ) . " The interior of the M42 Duster is divided into three areas : driving compartment at the front , stowage compartment in the center , and engine compartment in the rear . The driving compartment contains the driving controls and instruments . The seats for the driver and commander - radio operator are in the driving compartment . The stowage compartment serves as a base for the gun mount with space for 12 boxes of 40 - mm ammunition . The engine compartment houses the main engine , auxiliary generator and engine , transmission , and fuel tanks . The gunner , squad leader , and cannoneer ride in the gun mount . The squad leader commands , via the intercommunications set AN / VIC - 1 , either from the commander ' s seat or the gun mount . The 25 ton Duster is powered by a Lycoming AOSI - 895 - 5 6 cyl . fuel injected 500 hp engine . Operational History . Production of the M42 began in early 1952 at GM ' s Cleveland Tank Plant . It entered service in 1953 and replaced a variety of different anti - aircraft systems in armored divisions . In 1956 , the M42 received a new engine and other upgrades along with other M41 based vehicles , becoming the M42A1 . Production was halted in Dec . 1959 with 3700 examples made during its production run . Sometime in the late 50s , the U . S . Army reached the conclusion that anti - aircraft guns were no longer viable in the jet age and began field a self - propelled version of the HAWK SAM instead . Accordingly , the M42 was retired from front line service and passed to the National Guard with the last M42s leaving the regular Army by 1963 . Vietnam War . Unfortunately , the HAWK missile system performed poorly in low altitude defense . To ensure some low altitude anti - aircraft capability for the ever increasing amount of forces fielded in Vietnam , the Army began recalling M42A1s back into active service and organizing them into air defense artillery ( ADA ) battalions . Three M42A1 equipped ADA battalions were sent to Vietnam , the first arriving in late 1966 . Despite a few air kills early , the air threat posed by North Vietnam never materialized , and ADA crews found themselves increasingly involved in ground support missions . Most often the M42 was on point security , convoy escort or perimeter defense . The " Duster " ( as it was called by U . S . troops in Vietnam ) was soon found to excel in ground support . The rapid firing 40mm guns could devastate massed infantry attacks or sweep away guerrillas hiding in the jungle with equal ease . The Duster was both feared and hated by the Viet Cong and parked M42s attracted an inordinate amounts of attention from saboteurs . Post Vietnam . The last M42A1 equipped ADA units left Vietnam in 1972 and the Duster was returned to the National Guard . The U . S . Army maintained multiple National Guard M42 battalions as a corps level ADA asset until the system was retired in 1988 .