The M60A1E4 was a conceptual variant that explored using various remote managed weapons, such as a 20mm gun as secondary armament. A mock-up of this structure using the Type C turret was manufactured. Israeli variants: A lot of the Israeli M60s are actually upgraded with more reactive or passive armor, https://hoytmachineguns.com/product/sig-553-5-56x45mm-8-9-machinegun/