Well I am going to follow the lead of @ScoutingDad and favor the Illinois Central Gulf (ICG) but my addition will be a rather well known set by Mr. Marx that came under the heading "Work Train". It was offered in 1974-75. It consists of the ICG GE 70 Ton locomotive and a string of freight cars with the ICG name. For those of you who are interested in collecting sets of this sort, I will tell you that the hardest thing to find (unbroken) are the yellow side rails that go on the flat car and the next hardest thing is the IC searchlight car with the yellow generator. So here is my ICG work train.
And here it is with its set box...some prior owner put plastic tape over the box lid, I suppose to keep it closed when moving it (string would have worked so much better) and hence has really caused harm to the lit artwork.
Best wishes and happy "blue" Monday!!
Don