FM-1 : identical to the F4F-4, but reduced the number of guns to four, and added wing racks for two 250 lb (110 kg) bombs or six rockets.
FM-2 : based on Grumman's XF4F-8 prototype, optimized for small-carrier operations, with a more powerful engine (the 1,350 hp (1,010 kW) Wright R-1820-56), and a taller tail to cope with the increased torque of the engine. Four FM-2 Wildcats from Shamrock Bay's Composite Squadron 94 (VC-94) helped shoot down a number of kamikaze aircraft attacking Laffey off Okinawa before running out of ammunition.