I second that. The Lincoln Mark VIII cradle is the same design as the thunderbird's, and totally different than the Mustang's IRS cradle. As far as I know, the only parts that are interchangeable between the three is the diff casing. Control arms, half shafts, ect are all different between the Thunderbird/Mark VIII and Cobra IRS units.You used a Lincoln Mark 8 IRS cradle with Mustang parts on it? You're going to need to give us a bit more info on that swap.