Actually, sorry, it does not mean the seat has been removed. My 1968 280SL (113044-12-001155) has been in my possession since January 1973 and I have the vehicle data card. The transverse third seat has never been fitted. However, the DOT plate states three as the seating capacity. I believe this is strictly a US version issue and only in the approximate (!) period of 1967 to 1969. I would be please to hear more solid data.