X-Plan is sometimes called the "Friends and family plan." It is usually 4 percent over the A and Z plan price.
Here is a great link for more info: http://www.umd.umich.edu/univ/staffsen/forddiscounts.htm
Who ever calls to get your the pin number will give Ford your social security number. Then the financial guy at the dealer puts in the pin and the last four of your social. As long as that matches, you are golden.
I have used the A and Z plan (my dad is retired Ford Aerospace) for over 15 years and I have never had a dealership
refuse the pin number.
There is a limit to the number of X-plan numbers one can get per year. If you don't have anyone who can get you one,
let me know and I will see if my dad is near his limit.