Boeing 707-320C Evacuation

The 707-320C has a convertible passenger–freight configuration which became the most widely produced variant of the 707. The 707-320C added a strengthened floor and a new cargo door to the -320B model. 335 of these variants were built, including a small number with uprated JT3D-7 engines and a takeoff gross weight of 336,000 lb (152,000 kg). Despite the convertible option, a number of these were delivered as pure freighters. [source: Wikipedia]