Peachtree replacement single wheel roller
A distributor from Piscataway, NJ says:
May 7, 2015
Peachtree "Citadel" Sliding Glass Patio Door. Need one replacement wheel.
Paul from SWISCO responded:
May 8, 2015
You could possibly have our 81-112, but I can't be certain. The only way to know for sure what you have is to remove the original from the door and see how well it matches my suggestion.