just got back from a 2110 mile camping trip pulling my 38 ft 5vr that weighed in at 13,660. i got 11 miles to the gallon with my smarty jr set on tow haul mode. was well pleased with the power but the smoke was terrible. smoked up the rear end of my 5th wheel really bad. should i play around with the numbers or just deal with the tow haul mode. also, i put my truck into 4wheel low and i have the **** on the dash instead of the stick in the floor. put it in neutrual which to 4 w low put it in reverse to back the 5vr in and it sounded like a bomb went off in the rear end of the truck. unhooked the 5th wheel put the truck into park and turned it back to 2w drive and the light went off then pulled the truck out and everything is fine. switched it back to 4 w high then back to 4w low and had no problems. should i drain the transfer case and flush it and change the fluid again. 06 dual rear wheel. thanks for your help.