I did a quick troubleshoot of the fridge unit. It looks just like mechanic's, but much more well worn. The compressor and condenser assembly isn't exactly the same: the condenser is the cinnamon roll style, which are known to rot and leak. It seems to operate, though.
The evaporator looks the same, and made some gurgling sounds when plugged in for a minute. However, the freezer circulation fan does not spin. That seems to be the root cause of how it tore up.
Since the compressor sounds ok and tries to circulate refrigerant, I will stick some access valves on the service pipes so I can read pressures. If the freezer fan is bad, I have more little fans laying around.