Checking the Denver Public Library site -
Denver Public Library Photo Search
- I find photos of 482 in 1925, 1926 and 1928. She had the large numbers as delivered and kept them at least through 1926, showing the small numbers in the 1928 shot.
There are also shots of 487 in 1926 and 1928. Again, large numbers in '26 and small in '28.
None of the rest of the K-36 photos go back that far but I think it is safe to say that the engines were delivered with the large numbers on the cabs and were 'downsized' by 1928 after receiving their first repaints courtesy of the Rio Grande.
Baldwin had a habit of delivering locomotives in green paint, similar to the boiler jacket paint color. I have to wonder if the Rio Grande didn't just paint the engines black but left the jacket in close to the original green. Fun to speculate but all is, of course, lost to history.