There are no aftermarket gears for the trackick's that will help the high range. The only option is to change out the ring gears and pinions. If you have an automatic, chances are you have 4.67's, and you can swap the 5.12's from a manual kick. If you have a manual trans, you are pretty much stuck with what you have unless you can find a set of 5.62's or 5.38's. But these are scarce as hen's teeth and if you do run across them, they will be used.