Mine had the little tabs on top like your sign in question, but they are broken off. I assume it's to mount another sign to, "sound your Z" or "dealer".
It could be just a later version, because that is quite extensive metal work to fabricate the stand and ring and sign for an item that's only worth a few hundred to begin with.
I took apart a G&B T-8 pump built in the teens. I was amazed when I found a brass cotter pin in the plunger, that was over 100 years old and still good. They don't make things like they used to.
