 The wing modifications included outboard and inboard inserts, as well as a kink in the trailing edge to add area inboard.Takeoff weight was increased to initially and to with the higher-rated JT4As and center section tanks.Its first flight was on January 11, 1958; 69 turbojet 707-320s were delivered through January 1963, the first passengers being carried (by Pan Am) in August 1959.