Like some others have indicated, my primary interest is in another railroad. In my case, the Southern Railroad. But, as I'm sure a lot of you may know, the Southern and MoPac had some shared trains and the like during the 70's if not other times as well, so it was not unusual to see MoPac locomotives on Southern rails, not to mention freight cars out the wazoo! So I've been told a few times, before the Southern "got in bed with the N&W, there was some discussion of a merger between the Southern and MoPac.....but that it fell apart for some reason or another. 
I model the Southern as it was from about 1977 or so up to THE END. I currently have a few MoPac decorated locomotives that I intend to "super detail" in the future. I believe that when I get to that point, this will be a very helpful resource for information concerning getting my "off the shelf" models up to a higher grade of realism.  
Oh, did I mention, I really just like trains period!