Swapping 4.10 gears in the original axle is a simple and very worthwhile swap.
http://www.stovebolt.com/techtips/axles/1%20Ton%20Upgrade/Even though you can push the truck as it is and go faster like Jerry says the faster gears will make it more fun to drive at speed and burn a little less fuel.
Another option is swap the entire rear axle out for the right 14 bolt rear axle which have a range of gear ratios and brake options. Several discussions on the forum, check the 1 ton section.
I've done the first and planning to do the second, both have advantages and can work well.
