Hi Tomslin,
The SD files are only provided with some select solutions, such as Outbound or WFM. To find these, you will need to download the full CD or the individual Installation Package and then check the templates folder. For example, I just downloaded the latest 8.1.5 build of OCS and it included the SD file for the Outbound solution. As Jakub indicated as well, you can just as easily create them as well within GAX or CM.
Best Regards,
Neil