a 98 is Stainless steel exhaust manifolds, cats, & muffler assembly
(but the pre 98 has the heavier hi temp ductile iron exhaust manifolds)
BTW- can't do a direct swap as the header & cat flange changed in 98 too. Unless you cut & paste you need the 98+ header AND the 98+ cat to put these SS manifolds on a 96-97.