The switch from solids to vented came about halfway through the 98 production year. There are nearly as many 98s that take the solid discs as vented. The changeover happened around 3/98 or 4/98, and production of '98s would have started around 10/87 or 11/97.
Check the build date of the chassis (driver side door frame). Or the easier way is simply to look at the edge of the front discs.
Edit: With your initial post, I wasn't sure if you'd verified that they wouldn't fit. 