In production over 30 years, longer than any other armored vehicle, M113 and its many sub-types serve in the armies of more than 50 countries. Over 40,000 M113's or variants have been built and delivered by FMC or its licensees.
Battle proven in Vietnam, the M113 enabled a ten-man squad of infantry to travel behind protective armor in an amphibious vehicle that carried sufficient weapons to be considered an offensive weapons system. Its ability to ford streams or even cross lakes made it an extremely useful vehicle in the waterlogged jungles of Vietnam.
As experience was gained with the use of the M113 in combat, numerous modifications were made to the vehicle to increase both its firepower and crew protection features. M132 self-propelled flame-thrower was used by U.S. Army and ARVN units. M132 had a small turret equipped with a flame-gun and machine gun. A number of M113s were also used during the Vietnam war by the Australian armored units. They decided to mount a T50 Cadillac Gage machine gun turret.
The Republic of Korea Army units send to Vietnam acquired a number of M113s on permanent loan from the U.S.Army. The Korean Army's M113s did not have original designed gun shield kits as applied to U.S.Army's model. Instead, they did without the gun shield for the .50 caliber and had heart-shaped armored shields for the two .30 caliber light machine guns fired from rear personnel compartment.
