Add Shoulder belts to 66 Dart Conv?

Has anyone successfully added shoulder seat belts to a 66 Convertible? I am determined to get her running but have two young girls that need car booster seats still and I would love to add this safety feature.

Thanks!

Debbie

Would guess they were optional and the mounting points would be there. Just have to get the belts and bolt them in.

If there isn't mounting points not hard to add