Kit N-14 is the original Tutor. N-15 is the Gieseke Nobler. kits N-11 through 13 were the 1/2A stunt series Mustang, Cosmic Wind and Hurricane just for giggles and grins. All the stunt models carried the "N" designation beginning with the green box Nobler, kit N-1. If it's a complete set of ribs, I would be interested in them if you are looking to unload them for a reasonable price. Let me know.
Type at you later,
Dan McEntee