Amiot 350

The Amiot 350 was one of the variants of the 350 family that was powered by two Hispano-Suiza 12Y28/29 12-cylinder liquid cooled engines delivering each of them 920hp of power. It had a twin-tailed and was expected to be armed with three defensive 7.5mm MAC 1934 machine guns, one in the nose, another spinal one and a ventral one.
Considering how the French design of the time worked, the airframes were to be tested by as much engines as possible, to see which one achieved the best results. The first production contract for an Amiot 350 B.4 was placed in 1938 for 20 of them with a expected deadline delivery date of April 1939, however, 100 Amiot 351 B.4 were added to the order, and problems with the Gnome-Rhône engines destined for the 351 altered the order, so the order was altered and it was composed of forti-five 350 and seventy-five 351.
Those contracts were the closest point for a mass production of the 350 because in January 1939, it was decided that the fighters would have priority for the production of Hispano-Suiza engines, so the first order was altered yet again for sixty 351 and sixty 353 (although this one would never go beyond the prototype stage) so all the work on the 350 came to an end with just one prototype being built.

Sources:
1. https://fr.wikipedia.org/wiki/Amiot_354 (translated)
2. http://www.historyofwar.org/articles/weapons_amiot_350.html
3. Signal Squadron - Aircraft In action - French Bombers of World War II in Action