Obtain: Samuel Cooke or Philip Lem in Vault 19
Go to Vault 19 west of Vegas and speak with Samuel Cooke (or Philip Lem) to get this quest (Picture 1-2). Cooke will ask you to clean the sulfur cave of the geckos that live there, so go to the living quarters to reach the cave entrance (Picture 3) then eliminate all the mutated creatures you come across inside .
Report to Samuel (Image 4), he will then ask you to go to Red Rock Canyon to negotiate their admission to the clan with Papa Khan (Image 5). When he has accepted your proposal, return to Samuel to complete the quest (Picture 6).
Destroy the Sulfuric Cave for Philip Lem (Explosives 60) then convince him to join the Great Khans or surrender to the NCR
Destroy cave and shelter 19 (explosives 55)