I don't think so, the bumper covers on the 99-03 are shaped differently and kind of wrap around the larger opening more. The 97-98's are pretty much flat and pretty tight to the grille.
I have seen one going the other way (97-98 grille on a 99-03) and aside from a bigger gap at the bottom it looked like it fit ok.
This is the stock 99-03 bumper and grille setup. They use the same headlights and turnsignals as a 97-98.
I was looking at the way the grille and headlights are mounted today. I was looking at the two "tabs" behind each headlight, and after a minute realized that
IS how the headlight and marker light are mounted. This ought to be a pretty easy swap.
I also did some routine maintenance (at least for me) stuff on it today. I took the intake ducting all out and cleaned it. I also cleaned the MAF sensor and throttle body. It now is due for an oil change, and I can still see through the oil.
I added a new item to my "to do" list for the truck. It appears the alternator does indeed have externally accessible alternator brushes. So, I will probably go fork over some cold hard cash (3 or 4 Washington's) for some new brushes, housing, and keeper tool. Some people think I'm weird for doing this, but damn near every alternator that's taken a dump on me was because the brushes were bad and caused more issues.
EDIT: If anyone is interested, I did a little mini-write-up on brush replacement on my Ranger here:
http://www.therangerstation.com/forums/showthread.php?t=94951