The T-54 was a series of prototype American tanks of the 1950s with three different turrets, all armed with a 105 mm gun, mounted on the M48 Patton chassis. The T54 had a conventional turret with an autoloader with 3 shells, the T54E1 had an oscillating design with an autoloader, and the T54E2 had a conventional turret with a human loader. The turret on the T54E1 was similar to that of the T69 in its oscillating design and in that it held a crew of three and a nine-round drum autoloader under the gun. The T54E1 was abandoned in 1956 and in 1957 the entire project was cancelled in favor of the T95 Medium Tank. (Source: Wikipedia.org, CC BY-SA)