Here a link that will explain how to rebuild the steering box.
http://www.pavementsucks.com/tech/steeringbox.php

I replaced mine due to excessive wear on the box itself, I got a Lares steering box from advance auto. Do NOT buy a lares box, they have a lifetime warrenty and advance auto is good at getting a replacement, butI have been through 2 so far and this one is getting real sloppy, I plan on swapping it with another brand when the weather gets warm.