no idea mate, and that's the 2 different thickness's for the standard doughnut, the later ones were even thinner but seemed to have more metal in them in and around the bolt holes, lots of people say they are specific to the escos but i've seen them fitted to all sorts, probably something to do with ford sharing props across the range, withthe front bits being longer/shorter depending on if they were fitted to a granada, a sierra or a 4wd version