The M60 series was first introduced in 1961 and had a longer service life than any other tank, serving under nine U.S. presidents and eventually protecting soldiers in 22 countries with its thick armor. The 60-ton M60A3, one of the last versions of the series, improved on earlier models with a ballistic computer for fire control, a laser range finder, a thermal gun sleeve to keep heated guns from sagging, and an advanced thermal sight system that provided night vision. First accepted in 1978 and built by Chrysler Corporation, the M60A3 had a crew of four men, carried an M68 105mm gun, an M240 7.62mm coaxial machine gun, and an M85 12.7mm cupola-mounted machine gun, and was powered by a Continental AVDS-1790-2C 12-cylinder turbocharged diesel engine producing 750 horsepower at 2400 rpm. The last of the M60 series was phased out of National Guard and Reserve service in 1997, and this tank was brought to its final resting place on November 11, 2002.