'02 1500HD, 6.0, 4L80E, axle ratio unknown. The Wilderness goes about 7500, ready to camp. Add 6-700 lb for the 'Doo. Tow mostly in the flatlands, and short trips. Wouldn't want to do it with less truck.
Bought used in -08, had about 72K on it. Been pretty troublefree so far (crossed fingers), although it has just developed a windshield washer fluid leak. Coulda been worse :)
Get about 6 1/2 to almost 8 MPG towing depending. Due to higher aquisition cost, mostly short trips and so forth, never considered diesel, just didn't make sense.