Sorry I didnt chime in on this earlier...
Anywho, 00 was a half model year. They stopped production partway through the year to gear up for the launch of the LS430, LS400s were beyond scarce to see at Lexus dealers. Thats why you dont see many 00s.
As for HID on the 98s. MOST 98s have HID, wood/leather wheel etc. However it was an option that came in a package, made standard in 99. My dad's 98 had HID and the wood/leather wheel.
A couple other things, Air ride is very rare in all third gen LS400s, my dads had it too (the only one I've ever seen), and Nakamichi was rare in 99 (for some reason)...
And no laser distronic cruise on the 00, that came on the LS430 in 01. 98/99/00 are vertually identical in equipment, meaning everything was availiable the same. Only change in 99 was that the woodwheel/HID was made standard and electronic brake force distribution and daytime running lights were introduced. Only change for 00 was the availiability of the Platinum edition.