Information about the ending
http://www.labyrinth.net.au/~muffin/suspicion_c..html
I found this article really interesting, and thought i'd share. It discusses the various endings considered for the movie, as well as ideas for the first scene. I'm really glad they dropped the ending of Johnnie running away to the RAF!
It's interesting that no script exists for Hitchcock's letter ending. It makes me wonder if it's true that he had never actually intended for the film to end that way and wanted to make a movie about a 'woman's fantasy life' and only changed his mind after. I've read in several places that the commonly accepted idea that the studio forced the ending to be changed because Cary Grant could not play a murderer isn't true.
Anyway, the article discusses this in some detail.
Songbird, you've got tales to tell.