Thanks for all the compliments on the bike. The nacelle #? I need to look it up. It's in the softail section of the P & A catalog. I'm at work, and the catalog is at home. I haven't figured out what you mean by the "square hole" (unless i'm not seeing it). Anyway...the seat is only 1 of 2 that fit on the FLSTFSE2 according to the P&A catalog. I chose the Sundowner deep bucket seat...and yes it is comfortable. It does feel like it pushes me forward just a little, but after it gets broke in, i believe it will be just fine. Also...in case you are considering this seat, I did notice that it does not cover up ALL of the protective film on the rear fender. Probably 2-3 inches is still visable when you install the 2-up seat. The sissybar & luggage rack kind of hide it though. Nice thing is, I can change back to solo quickly. Christmas week! Busy..but I plan on taking some more pics because...... [smiley=worthless.gif]