Don't do much correcting on line to minimize flames, but:
Last post got it switched but on the right track. 18" SRW gets 3.31 or maybe 3.55 with certain options. 20" SRW only comes with 3.55 because of larger tire diameter. Ford gives very few choices of rear ratio assigning what they want you to have based on other options such as diesel/gas, drw/srw, heavy options, etc. Our 2012 sbcc srw with 18" and 3.31 flys with only 800 ft lb of torque. 60 mph up Mt Eagle mountain pulling our 9400 lb fifth wheel only half trying. The top gears in the 6 speed transmission are close together so rear ratio matters less.
