A contractor from Spring Hill Fl. says:
February 19, 2014
This nylon guide is at the front and rear of the vertical post of each door, it keeps the door over the center of the track. I have no manufacture name so I don't what else I can tell you.Thanks for your help!
Donna from SWISCO responded:
February 21, 2014
Thanks for posting! We are currently working on a possible replacement for this guide and will let you know as soon as it is available for purchase.
Tom from SWISCO responded:
March 4, 2014
Thank you again for your patience. Please see our new 86-026 and see if this could work as a replacement.