Be sure to use OEM belts. You likely with not be happy with the noise level or performance of aftermarket belts. Should be able to get the set for less than $30, the two OEM alternator belts come as a factory matched pair. Replacing belts is not a terribly hard job although the altenator adjustment bolt is kind of a pain to get at. You should consider getting the factory service manual or even a Chilton's or Haynes if your going try to do your own maintenance like this. They'll have all the bolt torque the belt tensioning specs., which you'll want to barrow a belt tensioning guage from a buddy in order to make sure you have them tensioned correctly.
Rookie.
Thanks Rookie, Does anyone know where to get a Service Manual for '96 Lexus LX450 or Landcruiser. Nothing available in my area.