The Xcal2 (X-2) comes in two different models, canned tunes only or custom tunes only. Depending on which one you have, the X-2 part #9400 only does custom tunes. The X-2 part #9415 only does canned, but can be converted to custom tunes only. I'm not sure how you would be able to tell if it has been converted. You might be able to hook up the X-2 device to you PC to power it up and read what tunes are in it. Usually the canned tunes will list as tow,street,performance. Where as custom tunes will usually show up as the name of the tune. ex
You can read more on this link.
What to look for when buying used SCT for 6.0
Here is SCT knowledge Base.
Edit: the '03-'04 trucks use a different strategy base than the '05-'07, so you won't be able to use the custom tunes that are on it already from the prior owner.