You probably don't know me, but for a number of years I used to run a
website called SoundAMerica before I sold it to the folks at advances.com. On that site is a collection of outtakes from the Thundercats and Silverhawks cartoons:

http://soundamerica.com/sounds/cartoons/Thundercats-Silverhawks/

When looking at your collection, I realized they must have migrated from SoundAmerica, since they are the same quality settings as the original WAV files - which, by the way, were converted using the MP3 codec, effectively creating MP3 files with RIFF waveform headers. I even know exactly when I originally put these files online - just over 8 years ago on August 15, 1997 - the day after they were given to me by Larry Franke, the sound editor for both cartoons. Here's a page captured on the wayback machine at archive.org:

http://web.archive.org/web/19980420051041
http://soundamerica.com/sounds/cartoons/Thundercats-Silverhawks/

I bring this to your attention, not because I want credit, but because you might be interested to know where they came from and who provided them - Larry Franke. You can see his credentials here:

http://www.imdb.com/name/nm1647770/