I would wager that they're something that was sold empty, to be loaded with drivers and electronics by the end user. The top panels look similar to some Acousticraft cabinets I had a while back. I would think they're worth a look, people that bought stuff like this didn't load them with junk. I've yet to find any real treasures inside stuff like this, but I've never found anything not worth the effort either.
To be clear, the cabinet in my photos was not a Fisher cabinet. I apologize, I should have been more clear. The owner had bought the cabinet new and then loaded in the Fisher gear. I don't remember any maker's mark on the cabinet.