#1 body style
#2 paid for
#3 the OBS has a tougher interior holds up to more abuse
i wouldnt be looking a new F550 if it wasnt for the larger 4 wheel disc brakes, 19.5" wheels, 6speed and a couple other odds and ends. still scared of the 6.0 though.....tring to find F450-550 4x4 crewcab...