The guys over at Coronado Scale Models have a similar photo and it is labeled Morenci Southern. Their photo is of the bridge with no train on it. It is also incorrectly labeled as Owl Canyon. I know that it is not Owl Canyon as I visited that bridge last April. This bridge as far as I can tell is the one across Negro Canyon down on the southern portion of the line.
If things go as planned I might try to visit the bridge site within the next couple of weeks and get a modern day shot. It would be nice to get one from the same perspective if I can get down in the canyon without too much trouble. Getting to the top of the bridge should be pretty easy.
Dave