Shoulder belt attachment on 68 post Dart

late response and i know you've already figured it out, but my 68 dart had holes above the pillar but no thread. which means it would be impossible to reinstall the seatbelt after headliner was up.

I've found helpfull posts here on old topics before so here goes...

so i got belts from retrobelt, welded some grade 8 nuts to square washers and welded those into the small space in the body panel behind the holes. then added a strong anchor in the floor for the retactor.
also welded some cross members behind the rear seat to hide the retractor for those so they aren't visible.