I also have a 98 and if you take the screws off then there are the 4 clips 3 on the top one on the side. It takes some yanked to get it off. I have taken mine off twice and one clip is broken from it so you might have to get some new clips but all you have to do is give it a little encouragement and it will pop out.

98.5 Black SVT with 34k miles Build #5683 Born on 4\15\1998 WR Headers GMK CAI Blaupunkt system fiberglass tweeter pods L.E.D. tail lights in the works