Unusual (RR?) Lamp Identification Needed

Please help identify this lamp or provide any information. Picked it up about 30 years ago in the height of my RR lamp collecting, always believed it to be a caboose lantern but have never found another one like it.

Attached is a close up of the only marking - it's stamped with the number 85 about 1/2 inch tall with the letter W in the top loop of the 8 and an S in the bottom loop of the 8, there's also a pair of wire handles that fold flat for mounting or opened up for handholds. I adjusted the photo to better see the marking.

It's made of galvanized tin painted black, I believe it to be a Caboose Lantern, or other type of signal lamp, however I've been unable to find anything similar to it searching for RR lamps, it doesn't have any other markings or name other than the 85. It measures appx 14 in tall by 5 in wide by 5-1/2 in deep and had three flat lenses with the option of any one of the three being in use at any one time or possibly two together as one position is stationary. They would have measured 4-1/2 square, the glass in the stationary position could be removed or replaced through a slot located under a flap on the top of the lamp, the other two through an open slot in the top of the swinging glass holder. The two swinging positions, when not in use slide inside, secured with a sliding pin. The rear has tang used to hang the lamp. The rear opens for access to the burner, directly behind the burner is a concave mirrored surface to focus or intensify the light. There's also a slot behind the stationary lens for what purpose I only guess was to attach a second lens of some type, perhaps for concentrating the beam further? The pictures show all sides, the front with the stationary lens and also with the two swinging lenses pulled out. Any help would be greatly appreciated!