67 Dart shoulder harness anchor?

I saw the rear shoulder belts pictured in another forum long ago.
I did own one 67 notchback years ago that had the roof anchors from the factory. Maybe it was a late build.
I have aftermarket anchors installed in the roof of my current 67. I wont install the shoulder belts to them until I complete adding the seat back latches though.
It's my belief that the seat backs should have been latched before the shoulder belts were offered.