of Defense drew up a series of requirements for a tank to enter service in the 1980s. The armored vehicle would weigh no more than , move at a maximum speed of , and cover at least on roads. It would be armed with a modern 105 mm main gun, two machine guns, and grenade launchers. The tank designers also had to take into account Argentina's existing infrastructure, including railroad capacity, bridges and road capacity, as well as the country's varied terrain. In late 1973 the Proyecto de Tanque Argentino Mediano (Argentine Medium Tank Project) was founded with the goal of designing and developing a tank for the Argentine Army. Lacking the experience and the necessary technology, the Argentine government sought collaboration with a foreign company, resulting in a contract with the German company Thyssen-Henschel. The contract called for a transfer of technology resulting in a program to develop a tank in line with the government's requirements and under a technical team that included both German and Argentine engineers. The hull of the German Marder armored personnel carrier was used, and the chassis was strengthened to support the increased weight of the TAM. Two prototypes were manufactured in late 1976 and early 1977, which were put through extensive testing for two years and over a road range of . Simultaneously, another prototype was manufactured to further the investigation of the new vehicle and complete the three prototypes as agreed in the contract. The new tank's firepower requirements were met by fitting a British Royal Ordnance L7A1 main gun. This gun was later replaced by the modified L7A2 and finally by Rheinmetall's Rh-105-30 gun. This gun is manufactured in Argentina as the FM K.4 Modelo 1L. The Rh-105-30's advantages include low weight, compact size and increased lethality. Unlike the Rh-105-30, the FM K.4 does not have a muzzle brake. The locally built cannon can be elevated to 18 degrees or depressed to -7 degrees on the TAM. The gun's hydraulic recoil mechanism has an extended length of to absorb the recoil force. It is designed to fire the M735A1 armor-piercing fin-stabilized discarding sabot, which can penetrate a maximum of at . It can also fire high-explosive anti-tank rounds, high-explosive squash head and smoke rounds. The tank's secondary armaments include a co-axial FN MAG 60-40 general purpose machine gun and a second FN MAG 60-20 mounted on the TAM's turret roof as