I just finished reading through your post in here from April, 2009.
I have no direct knowlege as to exactly what brand and color to use, but you might take some of the pictures you have found, and go to an arts and craft store, such as a Michaels, Hobby Lobby, or Joanne Fabrics, or where ever acrylic paints would be sold in your area, and see if you can find a close match.
There are so many manufacturers, each with their own color variations I think a hands on, or "eyes on" approach would have to be used.
Maybe someone in here that has recently painted a MILW. depot will chime in with what color matches they found.
Good luck!
Mike.
My You Tube
There did not seem to be any one shade of light or dark gray - of course I usually saw Milwaukee Road structures when they were well aged and weathered
I would not obsess about getting this or that paint to match this or that photo. Just about any light gray/dark gray combo should look realistic once it is weathered. Tamiya has some light grays; dark gray primer is a good contrast.
Dave Nelson
Would not matter even if you tracked down the original paint vendor for the actual depot and got a perfect match. It’s not just age and weathering that change colors over time. Ambient light changes things from minute to minute. Time of day, cloud cover, and secondary bounce lighting from the surrounding environment/structures. And season is huge: color does not render the same in sumner as in winter (Nor do shadows) . I’ve never understoood the obsession with prototype colors on anyithing. Unless you are modeling stuff that came out of the paint shop on a cloudless day at high noon, and you are using perfectly daylight balanced lighting on your layout, it’s a pointless endeavor. The color will shift the minute you moved anything, in time or space.
As I am aesthetically challenged, I showed my wife color photographs of some Milwaukee Road depots and structures, I then dragged her to the hobby shop and asked her to help me pick out the colors. We decided on Model Master Light Grey and Dark Grey RN (I assume the RN is Royal Navy). If does not look right, then I think I will just do some weathering to make it look worn out.