[Norbie]

The first GS300 sold here is a mk4 cressi, the mk5 started around 99 (give or take a year)

Actually the Lexus GS series is based on the JDM Crown, not Cressida. The first GS300 had the chassis code JZS14x.

S chassis = Crown.
X chassis = Cressida.

The "Mark II" badge lives on in Japan with the current X chassis cars, but they've long since dropped the "Corona" part.