QXD format has been used in some of the older versions of QuarkXPress and has been eventually replaced by QXP format. It is possible that latest versions of the program might still can save to the old format for legacy purposes, but otherwise qxp to qxd conversion will be difficult to achieve.
Perhaps some 3rd party document preparation program with broad format support may also be an option here, but overall the support for QuarkXpress files is somewhat limited.Open QXP file Open QXD file
A discontinued document indexer for Mac
A design software used to create rich documents for web or print
Software fro document design and publishing