Anyone knows Toyota part numbers for 2001 Lexus RX300 front and rear disc brakes.

if someone has some filespace, these questions will stop

Perhaps a way to get the info you want would be to use the search function here on Club Lexus. For example, in doing a search for "brake part numbers" in RX 300 sub forum, the search returned 10 results of which you might want to try this on in particular:
brake pad part numbers