On 31 August 1949, the French Air Force ordered 15 pre-production aircraft, which were later reduced to 12, in order to support the test program. The contract was signed on 15 December 1949. These pre-production aircraft saw extensive use in various flying trials and evaluations, including various engines, armament schemes, and equipment payloads, as well as to support other development programs. Amongst these aircraft, which were designated "M.D.450-1" through to "M.D.450-12", were several notable revisions; "M.D.450-6" was the first aircraft of the type to feature electrically operated trim tabs, "M.D.450-8" (also known as "M.D.450R", was configured as an aerial reconnaissance aircraft, and "M.D.450-10", which was used as a flying testbed for the SNECMA Atar engine.