Metal Bifold Doors, probably original, house built in 1967. Most doors have no markings, but one has instruction sticker. Weldwood Metal Folding Doors, US Plywood Corp, New York. No numbers or model info.
Bob from SWISCO responded:
November 30, 2020
Hello there. We've found Weldwood doors in the past use pins like our 21-002 and 21-007, but you'll need to compare the diameter of the pins and the diameter of the caps atop the pins to confirm they're what you need. Also see the 21-154 Pivot Rod Clamp and 21-277 Bifold Track Bumper.