"Lorraine de Dietrich", a company specialised in locomotive construction, presented a tractor and trailer to the "Commission de Vincennes" on 23 April 1937. The prototype was tested between 28 April and 10 June. Though at four tons heavier than specified, the type is approved by the commission on 8 July, with the period of testing extended to 23 August. Compared to the "Modèle 31", the Lorraine "chenillette" is much more a dedicated supply vehicle, the larger size of which allows for a superior carrying capacity, crew comfort and range, while its suspension with two bogies and four large road wheels ensures a good tactical mobility. On 8 September the commission concludes that there are no objections to series production; already the prototype had on 25 August been presented to the "Commission de l'Infanterie" at Mourmelon for tactical evaluation. Clearly the Infantry favoured this type but eventually it was decided to use all production capacity for the longer Lorraine 37L, as there was a lack of heavier movers; a first order of a hundred made early 1939 was in September changed into one for the other type.