Like a default installation of Mac OS X 10.3 Panther, a NetBoot installation image only includes the essential packages by default.
When you create a NetBoot image from Mac OS X 10.3 client installation discs on a 10.3 server, the image will contain the default selection of packages from the first two Panther discs. If you would like to add more than the default packages to the image, including the packages found on the third Panther disc, you'll need to create a custom image.
To do this, while in Network Image Utility, click the Contents tab, then click the Customize button (this button appears when you choose a CD or DVD from the Image Source pop-up menu). A dialog sheet appears, and offers various checkboxes for you to select the packages you want to include.