This is the complete download for Jailbreak 2004c (aka. Service Pack 3). It can be used for completely new installations or to upgrade any previous version of Jailbreak 2004.
This download is a plain 7z archive. To install it, simply extract its content to the UT2004 base folder, maintaining the directory structure and (if you are upgrading or reinstalling) replacing any conflicting files. The archive does not contain any configuration files, so you don't risk losing any settings.