Is this original to early Z's - 1970-71, or only later years?  To install it, you slip it under the center console, and run the forward most of the three back screws through the hole.  The straps hang down on each side of the transmission tunnel.  And you slip the inner most seat belts through the loops.  In theory, it keeps the seat belt from falling down to the floor in between the seat and the tunnel.

Mine is just like that and out of 6/72 car

Here is what the fiche has to say for the “Holder - Seat Belt” production history

Edited January 20Jan 20 by zKars

Even though the description says "holder", that appears to be for the belts.  

 

I don't see the part I am asking about in the car parts manual info.

 

I always thought it was when they changed to the retractable belts that have the larger buckle assembly. 

My '72 has those for the female lock like this picture. It's a 69,000 something or another VIN.

2 hours ago, siteunseen said:

My '72 has those for the female lock like this picture. It's a 69,000 something or another VIN.

Is that a BMW buckle receiver?

 I "hoovered" that picture off the internet from the comfort of my recliner so I don't have a clue.

The release button sticks up farther than my '89 325's did if I remember right from 20 years ago. Seems like it was flush with the housing?