This may have been posted, but I just found it. Interesting good read from How stuff works, on the 69-73 Imperials and the designers. 1969-1973 Imperial
That is a transcript of the article on fuselage Imperials in the April 2006 issue of Collectible Automobile. Recommended Reading!
Unfrortunately Howstuffworks.com doesn't have the companion articles on the 1969 to 1973 Plymouth Fury, Dodge Polara/Monaco or Chryser found in various other issues of Collectible Automobile.