Thanks Paolo!
1996 - 1999 Gen II oil pans are all the same and all 2000 - 2002 oil pans are the same.
The 2000+ pan will most assuredly bolt up to your 1998 and as Ron says, you get a bit more capacity. And to my thinking, an even more important upgrade for 1999 and earlier Gen II's, also as Ron mentions, get the 2000+ windage tray.
And then there's one more step, like Paolo mentions, some internal baffling (which can be applied to pre or post 2000 oil pans).