[Imadogman]

The XD exhaust/after treatment system weighs around 300 lbs. Gas engine without turbo probably loses another 300 lbs or so.

 

[Imadogman]

Pickuptrucks.com has a good first drive of the 5.6 gas. They also compare the torque curve of the new 5.6 to the old 5.6 The new one is much flatter and doesnt drop off as much after peak.

What I'm not sold on is the 7-speed. It is more of a 6-speed PLUS since 6th and 7th are so **** close together.

Let's compare the effective ratios of a Nissan 7-speed with 3.36 gears to a 6r80 with 4.10 gears:

7-speed : 6r80 1st - 16.9 : 17.0, 2nd - 10.7 : 9.6, 3rd - 6.8 : 6.3, 4th - 4.7 : 4.7!!, 5th - 3.4 : 3.6, 6th - 2.9 : 2.8, 7th - 2.6 : xx Ummm..... yeah, not much differance.

In fact, if you were to put 35" tires on your XD gas, 6th gear would then be VERY close to 7th gear on a truck with 33" tires.

With the additional 73 HP and 16 lb/ft of torque, it could change the drivability, especially while towing. Those who choose to run taller tires might not feel the need to regear with the additional power, especially if the torque curve is flatter.

 

[Imadogman]

I guess driving one will prove whether or not the gearing makes sense with the combination of HP, Torque, weight, and actual MPG numbers.
We will see...