The T58 Heavy Tank was a conceptual development alongside the T57 Heavy Tank, and while they shared some design similarities particularly being based on the T43/M103 chassis their primary difference lay in their main armament and turret design. The T57 was equipped with a 120 mm T179 gun mounted in an oscillating turret, a design inspired by French tanks like the AMX-50, which allowed for faster autoloading but came with mechanical complexity and limited gun depression. In contrast, the T58 was armed with a much larger 155 mm T180 gun housed in a conventional turret, designed for more traditional heavy firepower with greater armor protection and reliability. The T58’s gun used two-piece ammunition, similar to artillery shells, which meant slower reloads and a need for a human loader, whereas the T57’s autoloader aimed to provide higher rate of fire. Both tanks remained experimental and were ultimately canceled due to the impracticality of such heavy designs in the emerging era of more mobile main battle tanks.
