mrendahl, according to the 2010 towing guide that lists all the max safe towing limits, your truck is rated at 13,450 lbs max. Now, every pound of weight you put in the trailer and truck counts against this number. Don't forget the gcwr (truck & trailer combined), this # should be found on your drivers side door label. These #'s are not ballpark, they are max amounts provided by the manufacturer for each specific truck setup. The axle ratio difference between 3.73 and 4.10 on your model is 3,000 lbs (16,450 lbs for 4.10). Also the srw setup limits your ability on weight placed directly on the rear axle (5th wheel pin weight). Just some #'s to help explain.