The level 104 and 108 monkey zombies can be found under the Temple where Monkey Guards are located. The level 104 zombies are much smaller than the others, and the size of the monkey that the greegree transforms the player into depends on the size of the monkey that the bones were obtained from.
If you have a high enough prayer and combat level, these monsters can be used for training. With a high prayer level and combat level, you can get around 100,000 experience per hour. Use prayer, and when you are out run upstairs and use the altar. Make sure, however, to become a monkey using a greegree or you will be trapped by the larger monkeys up the ladder. An alternative to training here would be to bring prayer-boosting gear and use prayer potions, getting rid of the need to go upstairs and avoid the monkey guards. Remember to bring Salve amulet or Salve amulet (e), as they are undead.