Sliding door roller Approx age 1983
Hello,
The part in your picture is actually only the inside portion of the roller assembly. There should be an outer housing, perhaps still installed in the door. Since this appears to be an Allen Stevens part, the 81-278 patio door roller would be a good place to start. Ultimately, it will depend on how your outer housing and wheel dimensions compare to the image below.
To remove and install the new roller, you will need to remove the sliding door and the bottom door rail. Unscrew the two bottom frame screws (1/4-20 machine thread) and use a block of wood and hammer to carefully remove the bottom door rail. You will see on the inside channel where the glass was that there is another screw (10-32 machine thread) that holds the top of the roller housing to the door.