Taylor, there are a few pictures out there. I remember one or two of a 3000 series boxcar that was involved in a wreck in Ouray. It's in the CRM Annual 11 (pg. 157-158) and shows some of the lettering (the rest was destroyed in the accident). You may also want to check out the Otto Perry collection at the DPL's Western History Collection, since Otto started taking photos around 1913.
However one caveat... when the 3000 series boxcars were rebuilt around 1924, they were extensively rebuilt (they jacked up the number and rolled a new car underneath it) and almost all of the existing wood in the car was salvaged, often being used as part of the roof of the new cars, resulting in a car that bore very little resemblance to the old cars.