I first saw this image in the Thunderbird Illustrated magazine about 40 years ago. New club member Michael Ransom sent me a link to the photo. Rather than posting the link I just dropped the photo in.
The photo was taken on August 8th of 1955. So even before the '56 came out Ford was looking at some pretty radical changes. There are a lot of 1957 and 1958 hints in this design study. You can see what appear to be concrete blocks holding it up. This makes me think it was a clay model.
All I can add is thank goodness Ford didn't use that rear end design on the '57!