Get the outside of the box as clean as you can. Remove the 4 bolts from the end cap and remove the cap. The lower bearing and race will come with it. You can let the box drain as much as it will and then use some carb cleaner with the straw to clean a little more off the walls. Don't clean off the upper bearing or the worm nut, as you won't get any lube back into them. Let the carb cleaner dry out for an hour or two.
Pack the lower bearing and race and assemble. You may have to replace the gasket, or you may not. Either make one or use a thin smear of Permatex Ultra Black. Pack the rest through the hole as best you can! I like CV joint grease myself!
The manual calls for adjusting the steering shaft using a scale on the steering wheel to set preload. You can get away with guessing on this one, for the most part. First, loosen the jam nut and screw on the sector shaft. (The one everybody adjusts) Then loosen the big nut and adjust the screw accordingly on the steering shaft. (The one nobody adjusts!) Basically like a front wheel bearing, feeling where the bearing makes contact. Adjust it just a bit tighter so that there is a bit of resistance when you try to turn the wheel while unloaded. Since the manual shows the gearbox out of the truck, you need to have the wheels off the ground and use your best guess as to how much resistance is the bearing and how much is the steering linkage! Basically, take out all of the end play of the steering shaft and snug it just a bit!
Lastly, adjust the sector shaft screw.
