I did a search but found nothing. Anyone have any info on the MPG one can expect when carrying a heavy camper with a crew cab, 4x4, Duramax, 3500 DRW vs the same specs in a 4500 SRW? (I think both trucks have similar carrying capacity, about 9K.) The camper will probably weigh 5-6K lbs. That is why the 3500 dually or the 4500. Thanks for any experience. j