Keep in mind also that in 2005 and possible the two following years there was little difference in towing or carrying capacity between a F250 and an F350. My 2005 6.0 F250 crew cab short bed pulled my 40' FW TH flawlessly.
With your FW any of the 6.0 Fords should be fine. I have always had SB but if I ever go back to a FW I will probable go long bed just to eliminate the possible need for a sliding hitch.
On a side note I like people talking bad about the 6.0 so it keeps the price of the trucks somewhat reasonable. A few upgrades and they make great towing and hauling trucks.
