I don't have any pics. It is the defense verion with a plus 2 extender from the factory, pistol grip, etc. The sling mounts is fitted in a grove on the tube nut. It floats freely to allow the nut to be tightened and has three notches in the edge to allow it to be positioned to the left, to the right or to the bottom.
The more I think about it, it probably is supposed to remain free to ensure that when a sling is mounted it cannot loosen the magazine end nut (or whatever it is called).