The seats if you haven't pulled them out yet, are two separate sets. They both hook into the seat belt mounting bracket on the floor. I have mine both out for work, but put the left one in rarely for someone to ride with me. It would be difficult to use the existing floor bracket(seat belt) for two equal sized seats. The left would be fairly easy, but the right space being wider you might end up with a seat having extra space to the outside. I hadn't thought about that until now.