Seat belts in 1965 were a mere formality, if found at all.
We had a 1965 Chevy station wagon. We didn’t think it had seat belts, but they had just fallen between the seat cushion and seat back. No one cared.
My first car was a 1965 Dodge Monaco. It had seat belts and factory air. Leather seats also. The guy who had before me bought it in Detroit. 383ci four barrel. I loved that car.