Can this adjustment be done with the box on the truck or should you remove the steering box before attempting this?

If you have done this adjustment, let me know the best way to do this.

 

I don't see why not, if you can get to the adjuster. That's the way I've done it in the past on other vehicles. I would support the front end with jackstands, just to make it easier to turn the wheel to find center.

Have you seen this TSB?
http://dodgeram.info/tsb/1997/19-10-97.htm

 

You can do it on the truck very easily, follow the directions in the TSB listed above and you can't go wrong. You might want to think about hitting the large lock nut with some penetrating fluid every day for about a week before you try the adjustment.