WOW, nice review. Just FYI, if that thing does have the open diff 3.31 then that truck will be really fuel efficient. A 5.0 with 3.73 (heck an eco boost with 3.73) will never compete in fuel economy. But, comparatively, the rental you are currently driving has a max tow rating of 8100 lbs. The same motor with the max tow package (including 3.73 gears) has a max tow rating of 11,200 lbs. To compare it to your 5.0l (with 3.55 and tow package) has a max tow rating of 9500 lbs.

So, your 5.0l truck will actually tow more than the rental because of the gearing. Incidentally, the Lariat you test drove (with the max tow package) will tow more than all of the others. Incidentally, the fuel mileage will drop down significantly with each gearing change.

Additionally, the difference in torque numbers between the 5.0l and the 3.5L between 1500 and 2000 RPMs (which is the majority of us who are trying to increase MPGs try and stay) is as follows: The 5.0l starts out at approximately 212 ft/lbs (1500 RPMs) and climbs to about 240 ft/lbs (at 2000 RPMs). The 3.5L starts out at approximately 225 ft/lbs (at 1500 RPMs) and climes to approximately 290 ft/lbs (at 2000 RPMs). So the 5.0l gains approximately 28 ft/lbs of torque in that 500 RPM range comparatively the 3.5L gains approximately 65 ft/lbs of torque with in the same 500 RPM range. This is where most of us operate (especially driving up and down those hilly roads ). As you can see not only is the 3.5L running at a higher torque rating for the normal cruising range, but it also climbs even higher throughout this specific range. This is why (even with that low 3.31 rear end) the eco boost will out perform the 5.0L in this area and why the torque numbers are so important. So when your traveling at 65 - 70 mph down your favorite hilly road and wonder why the eco boost doesn't have to down shift from 6th to maintain that speed. Or when you are moderately accelerating to get to interstate speed, and your 3.5l also stays in 6th gear, you can credit the torque curve the twin turbos provide.

Please don't think I'm bashing the 5.0l because I have been researching both engines and both have my respect. But where we drive them the most (1500 - 2000 RPMs) the torquey little 3.5l will always out perform the 5.0L. But the 5.0L will play catch up (to a point) when allowed to downshift and get into it's higher torque range.

I tried to attach two pics depicting the hp and torque curves of both the 3.5l and 5.0L as measure by a truck magazine that was comparing the two motors in identical trucks. But, I could not find how to link the pics from my computer

Hope this is helpful.

Eric