Reinforced combat armor

In the Mountains to the northwest of Vault 3, slightly southwest of Vault 22 is an area with a lot of Cazadores. In the middle of their nests in the low hills is a duffle bag that has a bunch of weapons and the Mk II armor in it. The bag lies in the middle of a hole, you can see what look like wasp nests in the cliffs near it.

One can also be found in an abandoned truck inside The Devil's Throat next to the CZ57 Avenger Minigun, beware of radiation and centaurs.

One can also be found in the very SE of the map, in a cave beside the river. The armor is located in one of two duffel bags. Beware, there are a large number of Lakelurks in the area (at least a dozen).