4 decal variants:
1. MS 406 (No 1059), C.34, French Navy, Hourtin-Louley, France, 1940
2. MS 406 (No 798), Václav Cukr, 4th Escadrille GC II/3, Connantre, March 1940
3. D-3800 in full neutrality markings between September 1944/1945, Dübendorf, Switzerland
4. MS 406, 24. jovačko jato, 1. zrakoplovna luka, Zagreb, 1944
As an interim development aircraft, the twelfth pre-series M.S.405 had been fitted with the more powerful Hispano-Suiza 12Y45 engine and flown as the M.S.411, but a prototype of the M.S.412 with the still more powerful HS 12Y51 engine was not completed in France, the programme continuing in Switzerland as the D-3801. Flown for the first time in October 1940, the D-3801 had an HS 12Y51 rated at 1,050hp for take-off, a fixed radiator bath similar to that developed for the M.S.410 and the same armament as that of the D-3800. Although protracted teething troubles were suffered by the Saurer-built HS 12Y51 engine, series production of the D-3801 was undertaken by the Eidgenossisches Flugzeugwerke, the Dornier-Werke AG (Doflug) and SWS, deliveries commencing in 1941 and continuing until 1945, and a total of 207 being manufactured. These were augmented by a further 17 built in 1947-48 from spare assemblies remaining from the main production run.