Back seat's would be impossible i think...the base is ALOT deeper so the seat belts wouldnt poke through the seats i dont think, and IIRC the seatback catches and latches are in a completely different place than on Cav's...unless thats just on the Senator?
no idea. I didn't have my last Carlton long enough to look at the seat construction, and i've never owned a Senator. The most important bit would be the fronts, as from what I remember they're quite wide. I can probably work out a way to retrim the rears if needs be.