This stop still appears to be in use.  The yellow rectangle painted on the street is one of the main ways that Muni stops are marked (Muni can be weirdly backward in some ways).

The faded #16531 at the top is the stop number (which can be tagged as ref=.  The faded number at the bottom is the route (29). It looks like it's this stop: https://www.sfmta.com/stops/sunset-blvd-kirkham-st-16531