Left pair of engines Pratt and Whitney JT3D-3B. Those engines were unable to deliver pressurized air for aircraft systems, so mechanically driven compressors were installed on upper side of eng 2 and 3 pylons.
Douglas B26 Invader was used by Taiwanese Air Force from March 1954 to 1960. This is ex USAF c/n 28723 aircraft, bought by museum as no local remained.