Prototype helicopter; 2 built (factory designation PV-14).
HUP-1: Production helicopter with 525-hp Continental
R-975-34 engine; loaded 5,355 lbs; 32 built (factory designation
HUP-2: Production helicopter with 550-hp Continental
R-975-42; some modified for ASW as HUP-2S; 165 built; changed to
H-25B in 1962.
HUP-3: Former U.S. Army H-25A transferred to Navy; 50
transferred; changed to H-25C in 1962.
HUP-4: Modified HUP-2S; 1 modified (BuNo. 129978).
H-25A: Production helicopter for U.S. Army with 525-hp
Continental R-975-42; 70 built, with 50 transferred to U.S. Navy