Where do i find this guy to do the quest?

Do you mean Alice McLafferty?

She's in the Crimson Caravan Co.

If you mean Caleb McCaffery the bounty hunter, go talk to Francine Garret at the Atomic Wrangler (quest is Debt Collector)

Normally he's at the Wrangler, but if you reach the point in the quest where you have to kill him he'll be in front of Gomorrah

You say McCaffery, I say McLafferty. Let's call the whole thing off. :sadvaultboy:

Brain spasm there.

This whole quest is full of land mines. Last time I walked into the Wrangler after getting the quest and for some reason he was still in there. Mayhem ensued.