1967 1968 1969 back seats

Are 67-69 Camaro Coupe Rear Seats all the same? What are the lengths of std. Coupe Rr. Seats(top & bottom pieces)? What are the lengths of Deluxe/Convertible Rr. Seats(top & Bot)? For a 'fold down' Rr. Seat, is the Deluxe Seat required? Thanks----