Well, I just checked it out. (had some trouble finding this post again)
The 03 cap will fit on the front of a 2nd gen, but it's not deep enough to fit on the rear. The Dana axle sticks out further than the American Axle so the cap is about 1/2" away from where it should be.
The new caps have separate clips for over each lugnut, rather than the ring on the inside of the older ones.