Stock it will be fine. With an auto get 4.10 gears if you are pulling often and heavy. Your fuel mileage won't be as good though so don't be surprised. The only thing I don't like about my auto is the sloppy fluid coupling of the torque converter. If you upgrade the TC and Valve body you have to upgrade the flexplate and install a billet input shaft due to the added torque if you are pulling over 20,000 Gross combined vehicle weight. That is just part of modifying. Here is what I pull....

 

CumminsDriver I know I have seen that truck before but where…… Oh yeah on the Goerend site.

The most I have pulled is my old 98 4runner on a car hauler when I bought the truck. It pulled fine but the previous owner had pulled a fifth wheel with it and he had a custom plate in it. My trans is on its way out at 107K and next month should have a built Goerend in it. I will say it pulled nice with the TC locked but getting to a speed where it locked sucked.