Seatbelts---reuse or new?

The seatbelts in my '68 GTX needed attention about 25 years ago. I put them in a bucket of warm water with laundry detergent and some amonia. I stirred it around and let them soak for a day with occasional stirring.

Just check them for fraying along the edges at where they connect to metal. If the fibers are still tight, supple, and shiny, the belts are likely still good.