Fuel economy on Thor Super C

I am mainly looking at the difference in torque of a Diesel v Gas rig. I have a 2011 Ford F450 pick-up truck with the 6.7L Dually, long bed and King Ranch Edition (this is Texas guys!) I love that truck, strong, quiet, and pulls anything I own. Also, it is garage kept, YES-I do have a garage large enough to park it, 'cause I BUILT THE HOUSE. :) My truck currently is 2 years old with 22K miles and zero problems. MY pervious 2006 F350 6L had less power, was noisy and I was glad to trade it at 5 years old with 69K miles since the head gasket was replaced when the truck was 2yrs old. Thanks for ALL the GREAT comments and info.
Jer in Texas