Hi, Wild Turkey -
Welcome to Apple's Discussions.
You can download it from here -
http://www.versiontracker.com/dyn/moreinfo/macos/21044
The download link on that page takes you to another page at SmithMicro, where you select a demo/trial package for Stuffit Deluxe. Select the version for OS 9/8. A full working (non-demo) copy of Stuffit Expander is included in the package.
If you have no version of Stuffit Expander now, you will need one to decode/decompress the download.
That can be accomplished by using the built-in decoding/decompressing feature of Internet Explorer - in IE's Preferences, go to Receiving Files > Download Options, and checkmark the last two items on that page. Then do the download.
You can also obtain an an older version of Stuffit Expander from any OS 9 Install CD; there's no need to boot to the CD or run the installer. On OS 9.0.4 and later Install CDs, look for the Aladdin Folder in the CD Extras folder - dig into that, and you will find an uncompressed copy of Stuffit Expander. On an OS 9.0 Install CD, look for the Aladdin Folder in the Internet folder in CD Extras.
FWIW, I still use Stuffit Expander v. 5.5, which came on my OS 9.1 Install CD.