I think this is a Marine Sikorshy UH-34 heavy lift chopper with radial engines ... subsequent heavy lift choppers were turbo-shaft driven. Troop capacity was 16 and it had added forward facing cargo doors in the lower nose section. It's two radial engines were located in the external pods which allowed more cargo space in the fuselage. This aircraft appeared in the early days of USA involvement of Vietnam War (photo perhaps around 1963). Photo gotten from a friend and location may be Nha Trang but I'm not sure.