The helicopter in the movie 'Full Metal Jacket' is definitely a Wessex and a bit off an odd duck in that as well .
This pic allbeit not all that clear shows the four versions of the Wessex used by Royal Navy and Royal Airforce
The Helo on the left in the top pic is a civilian version with an unusual intake on the very front of the nose section ; Which is similar to the 'Full Metal Jacket' helicopter .
The main difference between the British Wessex and American H-34 versions are the different nose sections .
France used the early H-34 with the piston engine and the single exhaust pipe positioned low down on the port side nose section
Early American HSS-1 (Navy) and H-34A/C (Army) were similar
Later American version , particulary the USMC had a higher 3 exhaust pipe system
Westland designed their Wessex to use the Napier Gazelle gas turbine in their HAS 1/3 Wessex with two exhaust pipes either side of the nose/ engine section
Wessex HU-5's had the Rolls Royce / Bristol Siddeley Gnome Turbines with a larger single style exhaust cones angled slighty back on both sides of the nose section
The HU-5 in the pic above is really the same type of Wessex from the movie only the engine intake at the very front is different
Wessex nose profiles , HAS-1/3 at the top and centre right of page ; Australian HAS-31B Wessex centre left and the HU-5 at the bottom of the page
America did use a turbine engine version of the H-34 called the S-58T
The CIA operated some from Laos during the Vietnam War
Some U.S. Law enforcement Agencies also used the Turbine powered S-58T
S-58T nose/engine section
The last picture in Len Lundh's Sikorsky H-34 book is of these three abondoned Sud Est built H-34A's