You will need one of these kits to correct and adjust the bumpsteer on your Mustang, after making changes to control arm position or geometry, or if significantly increasing caster.
Bumpsteer is a term for the situation where the front toe changes as the suspension moves up and down. If the toe changes more than a very small amount it will cause the car to change direction, making the car unstable and unpredictable. MM offers two types of Adjustable Tie-Rod Ends. The tapered stud type can be used to make moderate changes to the geometry. It is best suited for use with a stock Mustang K-member, and does not require any modification to the spindle. The bolt-through spindle type has a much wider range of adjustment. It is required for most situations when installing a MM K-Member and requires drilling out the tapered hole in the spindle to accept a 5/8" bolt.