Ive been fighting this problem on my 2011, 6.7L SD. After a lot of talking Ford replaced my track bar ball joint, drag link ball joint, dampner shock @ 55,000 km, but it wasnt great and started even worse @ 130,000km. Took it to a driveline specialist and had to replace the ball joints again as well as the tie rod end, but also had a wheel alignment done and found the caster was out on the drivers side .6 of a degree. It is steering better now then the when it was new, so time will tell. It appeared to have been wrong since the factory.