Will my alternator that's in my 2001 rav work if I put it in my 89 tocoma pickup

If the pulleys, the housing and the bolts match, then YES. The only major thing that you'd have to worry about and check is check the Amperage output of the old Tacoma Alternator vs the Rav4 Alternator. You want the same or more output as the original. This can be found online or by googling the part number on the alternators (if they're still visible).