Those look like the AEV 6.1/5.7 conversions that were running around all week. If you've got $75,000 to burn, that's a great way to go.
:drool:
From what I gathered talking to the AEV folks, the MPG actually goes up with the bigger motor (the 5.7, which retains their cylinder deactivaction system) because it doesn't have to work nearly as hard to move the same mass. That becomes all that much more important when you start talking about 35"-37" tires, big axles, etc. There's only so much you can do with gears and a mini-van motor....
-----Matt-----