 By the late 1970s, Indian Army HQ had decided to acquire new-generation replacements for its UK-origin fleet of Royal Ordnance Factories-built Centurion and Vijayanta MBTs, which are based on the licensed production of the Vickers MBT, and consequently, paper evaluations concerning the firepower and mobility characteristics of the two principal contenders being offered for full in-country production—AMX-40 developed by GIAT Industries of France, and the Chieftain 800 (which later evolved into the Challenger 1 from Royal Ordnance Factories (then owned by British Aerospace PLC)—were conducted by the Indian Army.Between these two contenders, the Army had by early 1980 zeroed in on the 43-tonne AMX-40 MBT, which was still on the drawing boards and was meant to be powered by a 1,100 hp Poyaud V12X 12-cylinder diesel engine coupled with a LSG-3000 automatic power shift transmission built by RENK Aktiengesellschaft of Germany (offering a power-to-weight ratio of 25.6 hp/tonne, and armed with a 120 mm smoothbore cannon.However, AMX-40 had only marginal protection by the standards of 1980's.