Sorry to raise an old thread!
I am having a similar issue to the OP...
I recorded my old band ages ago (2003 - maybe earlier) using a classic iMac running OS 9 and Logic 5 (i think), and have just found the backups I made. The audio files appear as Unix Executable Files (see attachment), and I can't get any audio software to play them back for love nor money. I seem to remember the original file format being SDII (.sd2 or Sound Designer 2 format).
I have tried the system sound extension mentioned but it doesn't seem to work on OS X 10.8 and the original software developers email address just bounces every time I try to contact.
I have however, been able to extract the original audio from the files by importing the 'raw' data into audacity... but this is mega time consuming and would literally take me weeks!
I guess what I'm looking for is a bit of software that will batch convert the raw audio data into a readable .wav or .aif audio file, that will run on OS X 10.8.4.
Does anyone out there know a solution??
Any help would be hugely appreciated.
Thanks!