Currently I have a 2000 1500 quadcab 5.9 gas, 4x4, 3.55 gear, auto trans.with trans cooler and temp gauge, running stock tire size 245/16. Pulling a Outback 5th wheel -dry weight 6080lbs. I'll mainly be trying to go to Eastern Tennessee or Western North Carolina. I can get up most of the hills with out any trouble, but going north last year on I26 out of Ashville, NC heading to Johnson City, TN I got the trans. up to 260 and pulled over to let it cool before I made it to the top of the pass (can't remember the name of the Mountain - I'll call it a mountain, because the 18wheelers were having to gear down and go slow also). Trying to decide if I should go with a 4.10 or a 4.56 gear. Truck is only used to go to hunting camp and towing 5th wheel., so gas mileage isn't as important as pulling power. I live in the metro Atlanta, GA area.