Great information, Thai!!
Regarding the V8 mileage with full-time 4WD I am seeing very pleasing results so far.
I drive 70 miles a day to and from work(highway) and do regular 150m+ road trips. Since I live in downtown DC I also get a dose of city driving on the weekends.
I've just passed the 500 mile mark with my blue baby and if her computer is correct I'm averaging 20.5 MPG. Not bad for a muscular V8, eh?
Gonna be fun when I get my first foul-weather/offroad day...