tomarrow i am going to the pick and pull to get a new rear end for my trunk i tow my jeep with

at 75mph my truck runs 1400rpms with 3.42 gears i would to run 2200 to 2400 rpm what gears should i get to do this i would like to change the hole rear end and not just the gears it has a 10 bolt in it


350 motor and 700r4 trans

I don't know what ratios GM uses but use this calculator www.4lo.com

so that's 75 mph and 1400 rpm when in overdrive? I thought that when towing with an auto that it is best to avoid the OD. But if I use my mental calculator for the numbers you supplied then 4.88 gears put you in the 2300 rpm range.