I have stock engine mounts and the only change was that Shelby American radiused the lower corner of the LH mount to clear the side
oil gallery. I have since purchased NOS mounts from a Ford dealer and just duplicated the radius and they fit perfectly. Do you have them facing in the correct direction and are they for the full size Ford? I am not sure if the Fairlane or Mustang mounts are different but I always ordered for a Galaxy.