What seatbelt is this?

Buy all new belts.
From the 1970's your belts are over 30 years old, perfect or not. Think of the age of the material as you are trusting your life to it.
Maybe now is the time to put those three point/four point belts in you have dreamed about. Even NOS factory belts have outlived their useful life. Check with the Pantera Vendors, they have lot's of great options for you. Just don't put another set of 30 or 20 year old belts in.
Mitch

Dallas Mustang might be able to help.

1971 mustang ' grande'

You should check out a company in Tyler, TX called Snake-Oyl. www.ssnakeoyl.com or 903-526-4500. The rewebbed the belts on out 1865 Cadillac and provided a new set for the rear seats. They can probably rebuild yours and source the buckles if you'd like to keep them. If they can do polyester instead of nylon it would be worth the difference. I wasn't aware of some of this until recently but nylon belts can lose up to 50% of their strength in the first year. NASCAR has a two year limit even on the polyester belts.
More good info at www.english.scroth.com/racing and www.teamsimpson.com. The FAQ at Schroth is excellent.

Thanks guys. I guess I will check with the vendors, see if there is a modern replacement to fit the stock setup.

Hall and maybe the other vendors sell a set that fits in the stock location and it is a 3 point system. They bolt to the firewall and the retractor mechanism mounts in the inner rocker panel. when I recovered my firewall panel I covered up the area where the lower retractor was located.

Gary #06984