How about something unique??
For example, the LSST (Lake Superior Terminal Transfer RR) owned NW2's but could just as easily have had sw 1500's in thier roster and very well may have.
The unique thing about this Railroad is that it was Owned By the
Great Northern, Northern Pacific and the Soo line RR.
In the picture example you will see an NW2 in its well weathered and well faded colors.
Notice the home colors are the same as the GN or the BNSF example already given yet there is a Differance.
Rather than large orange stripes with green, Its is large Green Stripes with smaller Orange.The Green is NP green (very close to GN's Green)and the Orange is GN orange.
(The soo line didnt own enough of the line to have any say as to its coloring, they just got to pay a percentage of the Bills

The GN owned 50 % of this line which operated out of superior wisconsin transferring goods to all 3 RR 's classification yards.It is now a fallen flag with the BNSF handling all of its former operations in the Duluth-Superior Twin Ports Area.
Think of it as a smaller version of the Harbor Belt Line
http://www.rrpicturearchives.net/showPicture.aspx?id=9558