 Development continued with Sud-Est building two prototypes with a further refinement that led to the SE.2415, identified as the "Grognard" II, a two-seat development that included a stretched fuselage incorporating a raised cockpit with a bubble canopy and reduced 32˚ wing sweep back.Following initial testing, two boundary layer fences were installed on the outer wings of the SE.2415; underwing spoilers were also tested.Although neither prototype was initially armed, the planned armament array included two DEFA 30mm cannon as well as bombs and rockets.