I noticed a very bad vibration the last two weeks with my car and the steering wheel was actually dancing in my hands at 55-58 mph. I thought this was the thrust arms again but I just had them done two years ago. Went to a very good wheel shop and they balanced the wheels and guess what-the shimmy is gone! Before you shell out big bucks for the repairs, get your wheels balanced properly and with a good machine. Just a thought to consider.