I am wondering the same. If so, how do you go about signing up for it or is it just automatic?
X-Plan requires a pre-approved PIN that Ford would issue you if you qualify (IE: have someone who works for Ford or it's subsidiaries that is willing to offer you theirs, or belong to a large group that Ford sees as a trade partner, in my case, the MCA/SAAC, for which I have been heavily involved and a member of since 1981). You would get a code, then a link to the Ford "internal plans" site, fill out the proper forms, and the computer will issue you an 11 character PIN. You would then take that PIN and associated paperwork they email you to your dealer, who would then confirm your eligibility, walk you through your desired build, and input the order into Fords WBDO ordering system.
On another note, don't get too concerned on the default "19" priority code that I've seen posted about too many times over the years to mention. Any "non stock" order (IE: not dealer inventory), by default, is assigned "19". Yes, options can throw your truck into limbo as they await specific optional components, but is not necessarily due to a priority code.
Bill S.
PS: If you join the MCA just for the X-Plan, you must be a member for 90 days before you are eligible for a PIN.