Were Sholder Belts a Stock Option for '69 ?

While I've been finishing off the body work inside I noticed that there were two captured nuts in a location that might indicate that they were for Sholder Belts. See the attached two pictures.

The first is behind the drivers seat, I've circled the nut in question in the roof rail.



And the second is behind the passenger seat, again I've circled the nut in question in the door post.



If these were not used for Sholder Belts that the next question would be what would they be used for? Curious mind(s) want to know, all opinions and/or thoughts are welcome.

Thanks, Scott...

Im speaking out of my hind end here, purely hypothesizing... But is it possible that shoulder belts were an option? If so that may explain the nuts. Also a possibility is that since these were designed as work trucks that those may be "designated mounting points" of the metal divider used in the work trucks to prevent tools from hitting you in the head during an accident? Or the work cabinets option?

Not a bad thought and one that I had not considered as the one I have is the window/Sportsman model (the Basic version not the Custom). Does anyone else have these holes/nuts in these locations on their '69 or '70 Sportsman or for that matter on their panel van? Again just curious. Scott...

I would guess they are NOT belt mounting points.
A couple of reasons - not in the same location on each side, and the biggie, they are not reinforced to support a human body under a couple G's force in an accident.
Take a look at where belts are mounted in cars and trucks of the same vintage or newer and you will see plates, formed rails, and other stuff that are very strong.