Factory Harness Mount on Rear Bulkhead?

[Woodyhfd]

In the course of searching for threads on mounting child safety seats in the rear of a 911, I came across a reference to a rear harness mounting point (not the spot where you mount the three point seatbelts).

I removed the rear package shelf and I found a round knock-out in the insulation pad, directly behind the center of each front seat. I cut away the insulation and found a hole, but it didn't appear to be threaded or reinforced.

After I took the photos, I discovered another knock-out a few inches behind the first. I removed the insulation but didn't find a hole.

Is there such a thing as a factory mounting point for a racing harness or are these spots for something else?