This map is only available after the player finishes the epilogue.
The first treasure map can be found on the shores of the Sea of Coronado, southwest of Tumbleweed. There will be a corpse hanging from a cliff, shooting the rope and looting the body will get the map.
The second map can be looted from the chimney in Greenhollow.
Near Benedict Point, there’s a gutter on stilts running from a water tank on the hillside to the train tracks, for refilling train boilers. Following the gutter leads the player to the front of the water tower, which they can search. This will locate the third map.
The third map leads to Coot's Chapel. In the cemetery, there is a wooden cross directly under a tree. There will be a loose rock on the grave and under it will be the treasure.
The treasure includes a special horse stimulant, special horse medicine, a gold bar and a Crow Beak Trinket. That last one increases the amount of ammo the player loots by 10%.