A modular seat assembly including a seat bottom, a seat back, and a fastener. The seat bottom having a frame and a cushion, the frame including a first member having a channel with an open end. The seat back having a back frame, a back cushion, a second member, and a first restraint system. The second member is configured to be removably coupled to the first member by the fastener with the channel of the first member receiving the second member through the open end. The seat assembly is configured such that the second member may be decoupled from the first member to decouple the first seat back from the seat assembly and replace the first seat back with a second seat back.