A build sheet would be a cool find. Have you had the rear seat out yet? They are often under the springs on the seat bottom. In Barracudas they might be behind the bucket seat backs or above the glove box liner also.
Took the rear seat bottom out - not there.
Used a mirror to check under the fronts - not there.
Removed the front seat backs - not there.
Checked all around the glove box - not there.
Haven't pulled the carpet out. Might be a while before I get to that.
Not sure where else to look.