This article came out a while back:
http://www.detnews.com/2003/insiders...tos-117128.htm
Since then I have only heard more of the same. There is a thread on this board as well that goes more into this issue:
Gen III Lightnings, When?
The '04 L's will have the same body as the '99-'03's even though the regular F150's will have a new body. The release of the Gen III L with the new body is still uncertain.