Seat compatibility across the R model line?

[martinjmpr]

So I'm looking for a more comfortable seat and I have a question about the seat.

I realize there are mulitple R1150 platforms, the R, the RS, the RT, the GS, and so on. Do any of them share the same seat as the R, or does each one have a specifically tailored seat for that model? Reason I ask is that looking on Ebay and the likes, I often come across a spare RT or RS or GS seat, but not neccessarily an R seat. What I'm looking for, really, is a good seat pan and I don't care much about the seat itself as I plan on having something custom made. So does anyone know which seats, if any, interchange between models of the R1150?