Reference the question about cross-over steering. Its a common modification for 4wd trucks, especially if they are lifted, and it helps straighten out the steering geometry when the suspension and truck are going to be at extreme angles (rock crawling, etc.).
I have also see ads that suggest you can swap a 2WD box in for a 4WD box as part of a switch to cross-over steering. Since harder to find 4WD boxes, that would open up more choices for where to get a steering box if you could use a 2WD box on a 4WD.
Bruce