A 15 minute drive, half an hour of waiting in line, and this tape measure, and yet another 1" C-clamp, were the total treasure haul today. Sometimes you get a pot of gold; sometimes you don't. I take it the hex shape is a reference to nuts and bolts, although, frustratingly, it's not a true symmetrical hex. Still, it's a sweet little thing, and a neat piece of Bay Area history.
The numeric phone number (no alpha prefix) dates it from somewhere in the late 1950s/early 60s, when the old alpha prefixes went out of use. But no ZIP code, so I'm thinking maybe early 60s, since, after that, pretty well everyone put the ZIP code on addresses.
I briefly (two months) lived up the street from the dealership, and would go in and leave drool puddles all over the floor, although not for the Harleys: they had a sweet BMW motorcycle there. I didn't feel bad about the drool puddles, because I figured they probably had to clean up the oil puddles every day anyway...