You are in the CarrTracks website Picture Gallery.
While trying to get a lineup on April 21, 1995 I found this GP9 sitting by the engine house in the middle of Tucson. San Joaquin Valley 2041 seems a bit lost this far east of California. Disk 56
In 1950, Davis Monthan Air Force Base wanted to expand. To accommodate the expansion, the SP added a second track following the EP&SW from the east end of the yard in Tucson to near Vail in 1951. The railroad then ripped out the original track put down in 1880 between these points. You can't see much of the original route near Tucson, but out near Vail, you can clearly see in this Google map the old roadbed as it swings to the north following the river. Entire subdivisions now sits on the old right of way. The new track cuts across Old Vail Road. New US&S searchlight signals were installed in 1952 from Polvo to Vail 15 miles.