 Tranny or Rear Problem???
I picked up my 05 GT auto about a week or so ago. As it shifted from first to second I felt a minor shimmy. Almost like a vibration. It seems to have gotten better (or im getting used to it) over time. Figured it was under warranty and would have it looked at during the first service if it was still there.
Doesnt seem to hurt performance at all just a little annoying. Has anyone felt or heard of this before? I dont know if its the rear or the transmission or even something completly unrelated. It only between first and second when driving normal and it doesnt seem to be as bad there if im on it. | 
