I'm wondering how others tow. I tow a 9,000 lb fifth wheel with my 2002, 2500 auto with 3. 54 gears. I usually tow at 60 to 70 or so mph on the freeway in OD which is about 1600 to 1900 rpm's. At slower speeds or in hills or around town I turn off OD and run from 1900 to 2500 rpm's going about...