It was first referred to the M60-2000 Program and design work began in late 1999 by General Dynamics Land Systems as a private venture for the export market and was never evaluated for US military service.
Following customer feedback, detailed engineering work was carried out and in December GDLS decided to build a functional prototype.
An optional offering was to replace the torsion bar suspension with hydropneumatic units for improved cross-country ride.
The prototype of the 120S retains the standard M60 series power pack consisting of a Continental V-12 750 hp (560 kW) air-cooled, AVDS-1790-2 diesel engine with a CD-850-6 cross drive transmission, with a range of 275 miles (443 kilometres).
It was envisioned that production vehicles would have the more powerful General Dynamics Land Systems AVDS-1790-9 diesel developing 1,200 hp (890 kW) and Allison X-1100-5 series automatic transmission extending operational range to over 300 miles (480 km) but other power pack combinations were also offered as well as road wheels and drive sprocket being replaced by M1A1 components and the Abrams T158 lightweight track if desired.
The main weapon is a fully stabilized M256 120 mm smoothbore gun with a thermal sleeve as used on the M1A1 version of the Abrams tank and carries 36 rounds in the turret bustle.
The turret is fitted with two six-barreled, electronically fired M250 smoke grenade launchers, one on each side of the main gun.
[6] The electronics package used components designed by Hughes consisting of a 240X4 Forward Looking Infrared Red (FLIR) day/FLIR stabilized sight with an eye-safe laser range-finder, a Thermal Imaging System (TIS), an onboard digital fire control computer and data bus providing a similar capability as the M1 Abrams Mark 1 Advanced Fire Control System.
The Egyptian Army was considering this offer until it was finally rejected in favor of a licensed contract to build M1s in Egypt.