I was told by the local Ducati dealer that the only Scrambler with a different seat is the Desert Sled. All other are interchangeable. I can’t vouch for that being accurate but I know we have a FTP seat on a Full Throttle and it fits perfectly.
Ok, so I went to check out the seat and the only way it would fit is if I took off both side panels (the one in my profile pic) which I'm not willing to do. AND, even if I did, the older seat had more curve on the sides, so I'm not even sure that taking of those side panels would work. Max, I think you're right, that any of the Scramblers with side panels would be interchangeable, but not Scramblers seats from bikes without.
Cwitters, I get the impression that you could put the newer seat on the old bike, but not vice versa. I don't know that for sure though. I just know that the older FT seat would not fit on the new FT because of the side panels.