I have a 2005 Fatboy, but I really like the seat that comes from the factory on the Softtail Deluxe. Do any of the Deluxe's seats fit the Fatboy?

 

Not on an 05 Fatboy. The Deluxe was the first softail to use the new style softail seat mounting system. The other Softails changed to that system in 07 or 08. The Deluxe seat fits on a front tab and has two bolts in the rear fender like the old touring bikes had.