They are in the center of the Wastelands. They look just like Tyrants. If you know where Casian is, they are north of him. If you know where the broken statue is, they are all around it. Watch out for the Wild Desparado groups, they are aggro and nasty.
If you don't know either place, teleport to the Southern entrance and head due north, dodging Monster Eye Destroyers and the skeletons. You will cross a gully and see the broken statue just to your right. You should also see the Kingpins.