What you have is the equivalent of a 1980 hot rod that's been parked for a few decades. Not immediately useful, but could have some potential.
It is a "linear amplifier", meant to boost the power of a CB radio beyond the legal limit. As such it's technically contraband and Ebay will more than likely kick it off if listed there.
There will be one or two glass vacuum tubes inside. They were discontinued a few years after this amplifier was built, and are now pretty expensive. Any judgement of market value will begin with the condition and number of tubes. They have become sufficiently rare and sought-after that the tubes alone could have a higher market value than the amplifier in working condition. And if you have no way to test the condition of the tube/tubes, this muddies the water.
The 1980 hot rod would necessarily require some updating to hoses, gasket, seals and such.
This amplifier will need to have any factory-original electrolytic capacitors replaced. When they fail from old age, they can fail as a short circuit, overload and damage other components. Just plugging it in to see if it lights up is a risky move all by itself. There are precautions that will limit this risk, but only if you have the tools to bring up the power safely.
This amplifier could be newer than 1980, but not by much. It was designed to deliver as much transmitter power as possible without worrying about how long it will last. Hence the "hot rod" part of the story. In the same way that a hot rod often lands in a ditch, this kind of amplifier is famous for falling victim to abuse, whether intentional or not. Simply operating it with the adjustments set wrong can permanently damage the tube/tubes.
The model number alone doesn't tell us how many tubes it has in it. This manufacturer would change production details for any given model, with no hint on the outside of the cabinet how it is configured.
What you have is mostly potential. I would not recommend powering it up and trying to transmit with it until an expert has determined how safe this will be.
There is a running joke among electronics engineers that this kind of device is powered by smoke.
Until you let it out. And putting the magic smoke back in again is always more costly than letting it out.
73