Sliding glass door rollers replacement

Hello to you, as well! Thanks for posting. I believe you have a Harcar patio door, but unfortunately, they went out of business around 1990. It's hard to tell exactly what you have based on this picture, as this is just the inside portion of a complete roller unit, but I'd wager it's the 81-261. I would recommend checking your outer housing just in case. It should still be installed in the door.