[onewhippedpuppy]

We have a 2012 F150 SCrew 5.0 XLT 4x4 that's a really great truck. We bought it new and used it for truck stuff along with our family car for several years, and it was the primary tow vehicle for our 18' starter boat. My wife now has a Nissan Quest as our family truckster, and the truck is largely only used for truck stuff and the tow vehicle for our 23' boat. It pulls the boat at highway speeds, but the 6500 lb load and high drag reveal the one weak spot about the 5.0 - it makes torque fairly high for a truck. After a while it gets old on the highway, as the speed drops down nearly 10 MPH then the transmission drops from 6th to 3rd to power up the grade. I'm also planning another boat upgrade in the near future, which should only serve to make the issue worse. I need torque dammit!!!

So I'm kicking around a truck upgrade to either a 2012-ish F250 or Sierra Denali, either in diesel form. Obviously I really can't take either on a tow test drive, so I'm looking for feedback. Will either of them pull my 6500 lb of boat/trailer like it's not even there? For those that tow with similar trucks, what sort of towing MPG do you see? Any reason why I would be disappointed with the upgrade?