Wedge009 has extracted a set of MIDIs straight from Wing Commander III. You can download the set here. Here's his explanation:
I know there is already a ZIP of WC3 MIDIs in your files archive, but none of those files are named. After digging through the WC3 TREs, I found the MIDIs, so I've put together my own collection, similar to one put together by someone else for the Privateer MIDIs.
I'm no MIDI expert, but I believe Wing Commander III's MIDI files may actually be GS MIDIs (like those from Privateer and Armada). Does anyone know for sure?
All the MIDIs were cleanly extracted by myself, using HCl's TRE Manager as well as Ripper 5, and converted using Winamp (give credit where it is due). As far as I know, they are General MIDI format, and I have also added RIFF tags. Perhaps others might find it useful, I think it would be a good idea to add this to your archives - I have spent much time checking where each tune plays in WC3.