Shoulder Belts- 1971 Dodge Demon

I have both lap and shoulder belts on my car but only use the lap belts. Main reason being because I can't figure out how the shoulder belts work. I've tried every possible way that I can think of to make them fit and it just doesn't work. Any Ideas??
TIA
Kyle

The lap belt clip goes thru the slot in the shoulder strap clip before you click the lap belt into the main seat belt latch. I'm surprised you couldn't get it to work, it's not very complicated.

I don't know about your setup but my 71 Duster has one buckle for the lap belt and one for the shoulder belt.

My old '71 Duster was the same way, the 2 male belts (lap and shoulder) each had their own female buckle down in the seat. My Dad's '71 Swinger was the same way. Common for them to get pushed down into the seat, so fish around and see if the other buckle is there. Maybe someone took it out??