C&NW E-9Bm #503, Arlington Heights, IL, Oct 1980, photo by Chuck Zeiler

C&NW E-9Bm (also known as a E-9BA, E-9BS) #503, Arlington Heights, IL, October 1980, photo by Chuck Zeiler

It's difficult to ascertain the origin of this locomotive and exact model class, so check the links below for more information. My best guess is this locomotive started out as a UP E-6B #LA-5 (built Feb. 1941, c/n 1173) as part of the LA locomotive set (A-B-B). It was rebuilt by EMD in 1956 as E-8B #925B, but utilized two 12-567C prime movers, giving it 2400 horsepower. In 1973, it was acquired by the C&NW and given a cab. The cab was designed by then Supt. of Motive Power M. H. Crandall, thus it became known as a "Crandall Cab". At the time of this photo, the loco was the property of the RTA, leased back to the C&NW.

An editing note, as I was cleaning the scan, I almost removed an airplane, located between the top of the watertower and the pole to the right. Chicago's O'Hare Airport was close by.

http://www.utahrails.net/all-time/all-time-17.php#e6b-925b
http://www.utahrails.net/cnw/cnw03.php#501-e8