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).