Here are some additional photos of the sheath and stone. I didn't notice before, but the outer part of the snap on the upper strap has been moved. Both snaps are marked the same; TRW DOT inside the outer part and DOT DOT on the inner part.
The cuts in the belt hanger part of the sheath for the upper and lower straps look slightly different. The cut for the lower strap has rounded corners and the cut for the upper strap has squared corners. Also, the border stamping (tooling) of the straps are slightly different. So, I guess it's possible that the upper strap was added later. On the other hand, the wear on both straps is about the same, so the addition would have been made quite a while back.
In his description of this knife, Steve Zimmerman called it a custom sheath. I really have no reason to doubt that. Steve is a reputable guy and has been in this game a lot longer than I have.
- - Buckspen