shoulder belts for Daughters 65 Barracuda

And since I'm the lighting geek and we're talking about upgrading safety for compatibility with modern traffic: put in better headlamps (Cibie H4s if you want good but costly, GE Night Hawk H6024NH if you want decent and cheap, pick one of these two and ignore all other options unless you have a large pile of money to spend on super-premium headlamps) fed by relays, put in a good quality central 3rd brake light, maybe add DRLs, and upgrade the car's other exterior lights (see here for how, and here, especially post #20, for how not).

I wired in a six-inch wide low profile LED 3rd brake light on my '64 Barracuda. I used a piece of aluminum, bent into a crushed "S" shape, with some adhesive to affix it into/around the rear window seal. It was mounted on the inside, facing back--essentially where I think a "stock" light would have been. I ran the wiring up to the brake light switch itself (to make sure it it always went on with the brakes, since the original brake lights would sometimes not both illuminate if the turn signal switch was slightly off center).

It worked great and I really think it increased the rear visibility and safety during braking.