This GP7L was built for the US Army as number 1826 (builder number 15696) in 1951.  The Alaska Railroad purchased it in 1960 and rebuilt it in 1976 as GP7u number 1803.  In the photo above, number 1826 is in the Fairbanks yard in 1963.
Photo courtesy of James Sava
Retired Alaska Railroad Trainmaster
Color enhancement by Jack Klingbeil