Re: Flying Rio Grande Logo.

If memory serves me correctly, #499 was one of the very first.
The DPL photo archives has a series of pictures dated April 28, 1940, in which 499 and 498 are doubleheaded between Salida and Gunnison.
Helper engine #499 has Speed Lettering which does not look very recent, 498 the old style. That's a pretty early date for that lettering.
Dennis O'Berry reported to me last week that the earliest evidence he could find on the K-27's were both #454 and #464 in 9/40 in Montrose with the new lettering.
I'm not sure about the 480's and 470's, but in 1941, most engines of all classes had new lettering. It was a system wide change, and quickly adopted.