Along with 4 other cars, I have a 2000 RX300 with 290,000 miles on it, engine and trans have never been rebuilt, I do service the trans every 30K & pull the pan every 60K. I own a auto center and work on these RX's all the time and they are very reliable. However the last 3 trans problems I've seen were 2002 models and the differential in all of those RX had locked up and the trans had to be rebuilt. Not sure if that's a coincidence or a flaw in the trans/diff in that year. But overall from what I've seen these have been rock solid vehicles.
Joe
Operation Z
Northridge, CA