After the ending (spoilers)
Like others, I found "Quantez" to be a bit too talky and it didn't compare that well with other "gang in ghost town" Westerns. In passing, I might mention that the gang members were incautious with some of their pistol shooting - killing the collapsed horse and "shooting at shadows" in the bar - when the posse and Apaches were in the vicinity.
As with other Westerns where the beleaguered party is whittled down, there remains a story to be told after the final scene on screen. In "Quantez" the whittling down is formulaic, and one might happily bet a lot of money on whom one of the survivors will be and a little less money on another. The film ends with them still having an arduous journey with no supplies or water through hostile country. At least in "Shalako" and "Dakota Incident" (with their similar endings)one of the survivors was experienced enough to cope, but in "Quantez" ...