Elly,
The seats that turn have a square base that bolts thru the floor.
It should be fairly easy to replace the seats you have as long as you can get rid of the seat hardware under the current seat.
Also make sure that you have enough clearance to turn the seats.
They should be available in many places. There is a RV salvage near Carthage, Missouri for instance. I cannot remember the name but someone will chime in I am sure.