The cover features GB&W #312 entering the Green Bay turntable while an Alco RS-27 in Chicago & North Western colors sits nearby.

The January 1968 Railroad Model Craftsman magazine had two articles on the Green Bay Route.  This is the cover of the magazine.

At first glance it doesn't look that unique: a picture of Alco C-424 #312 entering the turntable at Norwood Yard.  But if you look at the background you can see one of the most unusual paint jobs that any Green Bay Route loco ever had.  RS-27 #902 sits in Chicago & North Western green & yellow paint with a "Green Bay Route" logo on the side of the hood.

Heavy traffic and high speeds in the late 1960s caused the Green Bay & Western to look for additional power, and they found it in the for of Chicago & North Western RS-27s #902-#903  The units kept their C&NW paint scheme with a "Green Bay Route" herald added to the cab side.   Because their M.U. equipment was not compatible with the GB&W's, the pair were typically assigned the local freight to Wisconsin Rapids. 

C&NW #903 was purchased in October 1968 and #902 joined the fleet on February 21, 1969.  The locos were renumbered to #316 and #317 and were the first to wear the all-red paint scheme.  #901 joined the GB&W in the 1970s.