Those are from a now deceased company called Hickey and while a couple were purchased by Mopar and sold as Mopar accessories, not all of them were.

As for the steps, here is a Chevy forum, with a pic of a Top Hand Ramcharger with one installed, and some info on the Hickey accessories:

http://67-72chevytrucks.com/vboard/showthread.php?t=778172

I myself have only seen two of these steps, both were on the passenger side and both were bent.  I assume the driver side steps were removed after they bent or broke, which could make it hard to open the door.  There is a similar style step that didn't fold down, but just slid outward when the door opened.  I have seen more of that style over the years, oddly on full size vans more than anything.

I would not consider these a "factory style step".  They were an add-on, and not a very good design, in my opinion.  About the only "factory style" step you would find in that era would be a set of the extruded aluminum running boards.  "Nerf Bars" as they were known in the '80s, or tubular side steps as they are known now, were not really a popular thing until the late '80s and I think they were first offered as a Mopar accessory on the BR series trucks in '94.  Somewhere around here I have a couple Mopar Accessory Catalogs for the D/W series, but I don't recall any side steps other than Westin running boards.

Kind of reminds me of a RV/Camper slide out step .

Kinda, but they swung down sideways (both from the front, towards the rear), and did not come out any further then they are in the top position, just swung down when you stepped on them. A friend in High School had a W150 with them. I think they were too shaky to use, even many running boards back then, would bend down when used. But the swing down steps would swing down, then bend down a good 2 to 3 inches when you stepped on them. Not at all on the level of RV steps of today.