Think it may be from a LC gate or ground signal. I saw a pic of one online but can't find it now.
Definitely not a horse carriage, not with those red lenses. It looks like it was designed to turn thru 90 degrees to show either red or white to oncoming traffic, white lights were once used in lieu of green to show all clear.
If it is stamped anywhere, it's going to be on the oil reservoir or the chimney, usually oppose the seam. Lots of them weren't marked at all though.