I've seen these a few times on other sites. Some people say there was a kit back in the day (late 80's I believe) that would convert the truck into a dually "look". Not functional though as it was just a simple adapter for the rear axle. It supposedly also came with the bedside extenders.
Now if he put a shortened DRW D60, that would be quite amazing!
As far as I know, there are no dually rear axles the width for a Ranger. Only fullsize.