Based on the evidence, I think that the only logical conclusion is that the 5500 series stock cars were painted red immediately after being rebuilt in 1926 and that the black paint came a few years later, probably starting with the next time the cars were repainted. That means that the 1926 rebuild lettering style (that Vic Stone categorizes as "Lettering Style 3") would have been applied to the newly rebuilt and RED painted cars in 1926. Cars repainted black before 1937 would have had this lettering as well.
The lettering that would have been on D&RGW 5743 immediately after being rebuilt in 1926. The car was RED at this point in time. (from page 155 of "Taking Stock") (D&RGW 5743 is the car we have in Como that will be restored)
Photos of the stock cars taken between 1926 and 1930 or so are somewhat hard to come by, though I did fine one on page 58 of "Taking Sock";
At first glance, it would appear to show two black stock cars in a train entering Durango. However, if you look closer, it becomes apparent that the "tone" of the color of the stock cars is a match to the boxcars that the train is passing and not the locomotive. Given that the locomotive is black and the boxcars are red, it would seem apparent that the stockcars are red as well.
A closer look at the photo. I have shown the photo in the book to a couple of people who do not know that the stock cars are supposed to be black and their consistent opinion is that the stock cars are the same color as the boxcars, which is a different color that the locomotive and tender.
What started this whole thing was a plan to restore D&RGW 5743 to its appearance immediately after being rebuilt in 1926. So, look for a red D&RGW stock car wearing the 1926 style lettering in Como next year!.
Jason Midyette