So, you are saying that Arning developed the drop as part of a complete performance suspension package for 4 or 5 cars? Well, since you can't find a Falcon with that set-up, and you can hardly find a Shelby with that drop only, I guess it is a moot point. Face it, Shelby is the only one who made the drop popular and did it to more cars in a year and a half than anybody else, therefore the term Shelby drop.Arning did develop the drop as part of a performance suspension package that did include IRS. Many 63 and 64 Falcons were tested on and it was these cars that the Mustang IRS was installed. 4 or 5 cars (all falcons but 1) got the original Ford IRS put under them.