I believe that Build Certificates were mailed to original purchasers at the end of the model runs, I have mine as I was an original purchaser in 1999. Certificates contain exact build information and detail the production number and date, vehicle identification number and where the vehicle was produced. You can call the Ford Performance Group for a new copy of the Certificate. They will need your name and VIN number. They charge $40.00 for this service now.
Ford Performance Group Phone Number: 800-367-3788
You can also order a Build Certificate directly on the Ford Performance Group/Ford Show Parts website. Again, the cost is $40.00. (+$10 shipping)