You indeed have an old Leigh bi-fold door. The pin you are showing is the top pivot pin. There should be a bottom threaded pin like the 21-062 for the door adjustment. The other two pins will be the top and bottom spring-loaded guide pins, the 21-058. You are correct on the cylinders, the 21-150 act as bushings for the pins to slide through the door holes.
Thanks for getting back to us. I believe you can use the 21-054 and two 21-150 nylinders on your door. You might have to knock off the top nylon cap to fit in the track bracket, though, so keep that in mind.
First, install the two nylinders in the door hole openings. Fit the spring in the door cut out and push up the pin through the holes and spring with the hole for the cotter pin near the top. Place the cotter pin through the pinhole with the spring below it. When you do that, you're putting spring tension on the pin to lock in the top track bracket.
Hopefully that works out. Let me know how it goes!
