Renault had been further developing the Renault UE from 1931 onwards. Some features had been introduced to the production series, some expressed into new prototypes; others had remained mere paper projects. Renault always strongly lobbied to attain official, and thus financed, state orders for his development projects and on 20 December 1934 he had managed to obtain one for an improved Renault UE, the Renault UE 2. One by one during 1935 and 1936 improved components were submitted to the "Commission de Vincennes" to be tested and modified according to the wishes of the Army. These included: reinforced pistons; a new gear box with four speeds forward and one reverse; a reinforced differential; longer front mudguards of which the back part bent upwards to form a continuous plane with the glacis, a semi-automatic attachment system for the trailer and a night light at the lower left back of the vehicle. These changes were not very fundamental — the commission was not even aware this was supposed to end in a new type — but Renault used this very fact as an argument to select the UE 2 as the replacement vehicle: the improvements could be introduced without interrupting production, whereas the switch to a completely different design might cause a fatal delay in the rearmament process. This proved to be a decisive consideration for the Army and November 1937 a choice was made for the Renault UE2 to become the type for mass production: the "Chenillette de ravitaillement d'Infanterie Modèle 1937 R". An order was placed with AMX — the nationalised former Renault factory — on 3 December. Other manufacturers were employed also: in fact Fouga had already obtained an order on 2 December; Berliet would be given one on 16 March 1938.