The M60 is an American second generation main battle tank (MBT). It was officially standardized as the Tank, Combat, Full Tracked: 105-mm Gun, M60 in March 1959. Although developed from the M48 Patton, the M60 tank series was never officially classified but sometimes informally grouped, as a member of the Patton tank family. The similarities can be noted in the original variant of the M60 and the M48A3. The US Army considered it as a “product-improved descendant” of the Patton tank’s design. The United States fully committed to the MBT doctrine in 1963 when the Marine Corps retired the last (M103) heavy tank battalion. The M60 tank series became America’s primary main battle tank during the Cold War. Over 15,000 M60s were built by Chrysler. Hull production ended in 1983, but 5,400 older models were converted to the M60A3 variant ending in 1990.
Source: M60 tank on Wikipedia