They make (OR MADE) the ARB for the 99.5-2004 pathfinders, but if you find one, it will fit the 96-99. There will be a bit of a gap between the grille and the bumper, as the grill on the older R50's are flatter.
That said, I understand they are not making ARB's anymore for the R50, unless you can find like 49 friends to go in with you. (there are a couple threads on this, have a search).
That leaves you with finding used bumpers (best of luck), going custom, or buying a KMA (who have now changed their name to TAG or something?).
http://www.tacticalarmorgroup.com/
They do have a reputation for VERY long waiting times.