Yes, and remember it drops down fast! Two adults at 200 pounds, 1 or two kids total of 150 pounds, nother 150 pounds of cargo + WDH and you're at 500 pounds off your specific payload (1450, now at only 950 pounds tongue weight remaining). So now the max trailer you can pull = 10-12% of payload = about 8000 pounds of towing.
So though the truck can pull more, it is actually limited by the required tongue weight of the trailer. That is why I didn't get the 3.92, you can't actually tow anymore than the 3.21 (though at max loads your setup might be a little less stressful on the drive train at take off than mine).