The four in the back layout was called, not surprisingly, the 'four on the floor' configuration. It was a utility, high density configuration. The seats were nothing more than pads, each with a seatbelt, and it required that the passengers sit with the opposite passengers legs intertwined. It has been used by military special operations, SWAT, utility operators and sky divers. Have not seen a 500 equipped in that configuration in a long time.