You are wrong on top of wrong.
The Thunderstorm name wasn't applied to the XB's until the 2005 model year.
Oh, wait... are you the guy selling a 1998 Buell (by Harley Davidson) Thunderstorm S3 on craigslist? Make sure you copy the info from motorcyclespecs.co.za site into the ad for that buyer who has no clue as to what they are buying, but the price is CHEEEP!
I dont think the tube frame models were ever called Thunderstorm, but some of the later ones had Thunderstorm heads. I think they were all called "HVPS 1203" which I understand refers to the breadbox more than the motor. There was the S2/S3 Thunderbolt models which may or may not have had Thunderstorm heads. ugh.
your pal,
-Capt. Condescending Ahole Pedantic