The continued use of gasoline engines was undesirable due mainly to its high fuel consumption, poor low-end torque and fuel flammability. ARCOVE industrial representatives had expressed desires for a diesel engine for the tank since 1953. Continental Motors and OTAC began to develop an experimental X-shaped vapour-cycled engine design powered by hydrocarbons in 1954 for the T95 tank but it remained unreliable. In June 1955, OTAC adopted the recommendations and allowed a diesel engine to be used if it significantly contributed to better fuel economy. By August 1956 the diesel powered AVDS-1790 was recommended for the M48 and the Army requested the initial retrofitting of approximately 1,020 older M48A1s and A2s with the new engine in December. By February 1957, the US Army had around 600 converted M48A3 Patton tanks and the US Marine Corps had received 419. The A3 model incorporated a diesel engine which greatly improved its cruising range. Because many M48A3 tanks were conversions from earlier models many details varied among individual examples of this type. M48A3 tanks could have either three or five support rollers on each side and might have either the early or later type headlight assemblies, some retained their earlier Mod A turrets and different cupola styles.