Re: Harrisburg Car Co.'s Exhibit
For what it's worth, Micro-Trains has done a "Merchants Despatch Four-Pack," a "White Line Four-Pack" and a "Red Line Four-Pack" in N Scale on their Civil War Era cars. I anticipate there will be a "Blue Line Four-Pack" at some point as well. These photos plus the one in the Merchants Despatch book appear to be among the source material Micro-Trains used.
Interestingly, according to the Merchants Despatch book, the MDT had already stopped painting their own cars by "color line," preferring to go with a less-restrictive MDT scheme-- though the red, white and blue stripes at the bottom of the "classic" MDT refrigerator scheme are a reference to those three Fast Freight Lines. So it's not surprising that the 1876 photo has White, Red and Blue line cars lettered for railroads in the New York Central's "family tree."
George "you've forgotten more than I know" Irwin