Rushed to Vietnam in January 1969, the 16-ton M551 Sheridan armored recon-naissance/airborne assault vehicle was designed so that it could be parachuted from aircraft and swim rivers. Its M81 gun/launcher fired conventional ammunition or an MGM-51 Shillelagh guided anti-tank missile. Although the M81 had problems and the M551 was vulnerable to RPGs and mines, the vehicle soldiered on with the 11th Armored Cavalry Regiment, left. (AP Photo)