I am looking for more information about the Holster for the Sling Gun of the Supertrooper Suit.

Looks like, they have taken the Sling out of the "Kaisers" Shaft and worked it up into a separate Holster.
Here’s a picture of my Sling gun so far.

Here’s a comparison picture of the Sling clip from my Gun and the origin picture.
I think the clip from the Sling took place in the picture below:

Is there anyone, who has more information about the holster?