Bell FM-1 Airacuda - version overview:
XFM-1 - prototype escort fighter, V-1710-13 engines
YFM-1 - V-1710-23 engines
YFM-1A - nose gear
YFM-1B - V-1710-41 engines
YFM-1C - project with engines in the fuselage driving the pusher propellers in the nacelles
Source:
http://www.aerofiles.com/_bell.html
http://en.wikipedia.org/wiki/YFM-1_Airacuda
http://airplane.designation-systems.net/index.htm
XFM-1 - prototype escort fighter, V-1710-13 engines
YFM-1 - V-1710-23 engines
YFM-1A - nose gear
YFM-1B - V-1710-41 engines
YFM-1C - project with engines in the fuselage driving the pusher propellers in the nacelles
Source:
http://www.aerofiles.com/_bell.html
http://en.wikipedia.org/wiki/YFM-1_Airacuda
http://airplane.designation-systems.net/index.htm