You need the Shelby registry and there is a plate under the hood with the numbers. They are no secret and won't give away your location or any other personal data if you are worried about posting the numbers. People here are great and will give you the straight scoop, but you will get some pokes and jabs if things seem suspect and expect some critics, but that's just life! I hope it turns out to be a great find for you and your family!
Here is a picture of an early AC Cobra vin plate I took a couple of months ago (notice the standard CSX followed by FOUR numbers, not THREE):
