I re-looked at my link and I notice 98 was missing. 96 to 97 said severe 60,000, then it said 99 to 01 90,000. My Toyota manual for 2001 says 90,000 and so does Gates (the link I provided.) Understand Gates is trying to sell as many belts as possible.
That seems strange that the manual says 90,000 for severe. Maybe someone else with a 98 can chime in.