This is as good a place to start for my first post.
There were three places where a permanent VIN was stamped on an early Mustang; the exposed one on the left front fender apron in the knotch between the second and third fender bolt; a second one hidden on the same side under the edge of the fender roughly between the fourth and fifth bolt; a third one, also hidden, on the right hand side, in about the same place as the one on the left side. The door data plate was not a permanent identification marker and are subject to door replacement or car painters ignorance. Reproductions are available from
http://www.martiauto.com for about $30. If the title has a number 9 in the fourth position, as in 5R09x123456, you may have a correct title for the car. Otherwise, who knows.
Jim
(Is this OK, Glen?)