I've been shooting a lot of these the last few years, because dealers basically don't use them anymore thanks to laws in many states requiring the customer's permission to put a plaque on the car (the last three cars I bought from a dealer had license-plate frames instead, because they're easily removable by the customer).

Trying to find out information about the dealer is kinda hit-or-miss. If they're still in business, even if it's under a new name, it's pretty easy to track down. In other cases, the best I can find out is that they're no longer around. It's especially difficult if it's a discontinued marque like Studebaker or Packard.

I searched this one earlier today, and the best info I could find came from the owner's obituary, which said he started a real-estate business about 1975. That would suggest he got out of the car biz about that time.