Here's what I have:
Stewart Chevrolet Co
780 SERRAMONTE BLVD BX K
DALY CITY, CA
Now checking through old ads it looks like Stewart was at this address 1972 and after. Prior I see a Stewart Chevrolet at: 3146 Mission. Both either in San Francisco or on the out skirts. I would call Stewart Chevrolet still located at Serramonte and ask for an owner or someone who has been around many years and see if the same Stewart was originally located at the Mission address. If so, I'd be pretty confident that this is the correct dealer for that zone and code.
https://www.stewartcars.com/ Their website does say since 1933. I do see ads for Stewart Chevrolet beginning in early 1934 located at the Mission address so pretty confident it's the same company.
Paul