I forgot that I was going to post some of the features found on the factory two-tone guns ("pintos"). Here's a few iPhone photos of the cylinder underneath the extractor (notice the "N" for nickel)...
...and the grip frame (notice the "B" for blue)
Although not unique to pintos the yoke frame shows a much less common engraved pinto designation - "MOD-27"
Thanks for your likes and comments,