The Z-9 Crotalus DNA preservation lab is a location in Big MT. It is northwest of the X-8 research center in the Fallout: New Vegas add-on Old World Blues. There appears to be nothing of great importance in here except some very tough night stalkers and a lot of night stalker eggs, tails, blood samples, etc. along with the notable loot below. The Auto-Doc Upgrade: Implant Y-3 is guarded by the named night stalker, Shadis.