ford has notified f250 owners of shutter problem with steering effects, they claim tire pressure as cause, this vehicle has had this problem since purchased new, dealer has been notified several times up to 3rd year (end of basic warranty) vehicle still running on o.e.m. rubber, no excessive or unusual wear . steering box failed after shutter incident, would not allow left turn, box locked at midway rotation with definitive stop, forcing steering full right then full left, a pop / crack occurred allowing resistive left turn, box locked up several times while trying to safely exit highway. former ford certified mechanic inspected vehicle advised replacement as repair of box was not an option. several attempts were made to locate rebuilt box, none were available. new steering box was purchased from ford,box was only available with old box exchange, ford is obviously aware of this problem, no rebuilt avail? no exchange no box? i think ford needs to come up with a better idea!!!