Tech's on target as usual, with 33's and 3.73's you'll be doing only 1850rpm at 70 running down the road in OD, and your lower gears are going to be anemic. Going to 4.56's you're still only 2262rpm at 70mph, and with 4.88's you'll be turning 2421rpm. You need to look at how you want to use the truck, and pick your gears accordingly but that 700r4 has a 0.696 overdrive in it, so you can afford to go shorter on the gears and give yourself more pulling power, especially if you're wanting to off-road any.