I've just been doing it today. The bolts are either side of the rails 15mm.
One of the rails extends all the way and is shared by the middle row single seat.
I've just removed the back row seats, so had to remove the long rail and slide off both shuttles, then replace the shuttle for the middle row seat and bolt the rail back down again.
I took the short rail out completely. I did consider putting the short rail back instead of the long one but the bolt pattern is different.