67 Dart shoulder harness anchor?

My '67 aint got 'em! My Brother's '67 doesn't either. I would like to see about adding them to my '67 GT. I have a '71 for parts I was gonna pull the headliner back & see if it can be done.
There was also supposed to be an option on the later Darts for REAR shoulder belts too, but I have never seen them. Anybody else?..