I found this historic 1970's era Chicago area railroad photograph at my Link page Fallen Flags.Org, which is located to the right of your computer screen at www.rr-fallenflags.org
One of my favorite railroads I had grown up with on the near southwest side of Chicago during the 1970's, was the former Illinois Central Gulf Railroad. This railroad was created from the August 10th, 1972 merger of the Illinois Central, and the Gulf, Mobile & Ohio Railroads.
Although the official color scheme of the Illinois Central Gulf was the orange and white that the Illinois Central began using in 1967, it would take several years for the ICG to get around to repainting many of the locomotives. There were locomotives and cabooses that were still rolling around in 1960's era factory paint from both former railroad companies in to the mid 1980's on the ICG. I recall that it was a very colorful if not paint faded railroad.
Railfan photographer Dennis Schmidt, photographed former Gulf, Mobile & Ohio EMD GP 35 still wearing 1963 era G,M & O paint and markings, at south suburban Homewood Illinois on August 25th, 1974, two years after the merger that created the ICG. I liked the ICG for several reasons. I believe that the main one, was the variety of color schemes. This is one of the reasons I model the former 1970's era ICG today in H.O Scale.