 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 air-cooled, AVDS-1790-2 diesel engine with a CD-850-6 cross drive transmission, with a range of 275 miles.It was envisioned that production vehicles would have the more powerful General Dynamics Land Systems AVDS-1790-9 diesel developing 1,200 hp and Allison X-1100-5 series automatic transmission extending operational range to over 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.