5" square sidewalk drain grate / cleanout cover

There should be a name on it, or on the part imbedded in the driveway.

Been down that route and may prove helpful yet. There sometimes is. Ones I've found so far are either custom names of homebuilders long since out of business or contractors / suppliers equally defunct.

You went to real plumbing wholesalers?

If it's steel, maybe you can get it welded. If you want an exact replacement for historical reasons, try an architectural salvage yard. I saw a TV show a few years back about a large architectural salvage place in Oakland. I don't remember the name, but a Google search came up with C & K Salvage on Douglas Ave., and Berkeley Architectural Salvage on 65th St.

Considering names, I see a lot of drain covers labeled "city of " (city of BLANK).

I would think a local, commercial plumbing supply house would know exactly what you have. You may or may not be able to buy just the lid, sometimes it's cheaper to buy the entire assembly. Again, they should be able to tell you. There are a limited number of manufacturers who make these things. One of the big ones is Josam, here is a picture of a square hinged grate - you might browse here:

replying to trippknightly, Mike Hummell wrote: They have those drain covers at Discount Builder Supply in San Francisco and at Home Depot in Colma. Currently they come with a protective film on them. In the past they were just plain steel, so I would spray them with a galvanize paint to prevent (or delay) rust.