Since Testors discontinued both the Polyscale and Floquil paint lines in 2013, railroad modelers' stashes of these paints are starting to get low or may be gone completely by now. Fortunately, Model Railroad Hobbyist has provided the Guide To Acrylic Painting that makes up for this disaster (may sound extreme to the lay person but not to a model railroad hobbyist).
Here is just a minor example of the information available in the guide.
Erie Lackawanna (EL) gray
EL Gray is just slightly darker than Concrete gray. VMA 71.045 looks like it's a very close match. In the MRH chart 71.045 is listed as a stand-in for concrete, but it's a bit too dark, so the Vallejo concrete gray formula in the book makes a slightly lighter, warmer gray.
Vallejo Model Air 71.045 - US Light Grey / Cement Gray is what I'd select for EL Gray.
Color chip facsimile
Vallejo Model Air 71.045 - US Light Grey / Cement Gray
You can get Vallejo Model Air and Game Air for $2.39 per bottle (28% off) at Scale Hobbyist online. Of course, it's best to buy more than one bottle of paint to save on shipping - unless you are near Nashua, NH.
For the other paint brands...
Model Master ... 2 parts MM 4633 (Grau RLM / Gray Hue), 1 part MM 4609 (Light Ghost Gray).
MODELflex has this exact color in their line: 16-51 (Erie Lack Gray).
I want to emphasize that this is just a very small sample of the information available in this guide. The guide is available for download HERE.
If you have an idea for a blog post here, let me know. If I can comment on it, I will or I'll see if someone else can and post it.