It's only version 3.10b
If you get the latest version of Dede (aka 3.50.04) it comes with a nagscreen telling you that you shouldn't use Dede to decompile Delphi stuff in order to make money with it except if you contact Dafixer in order to get a commercial agreement... which means that the author wants to make money with his software :
So i doubt that we'll ever found sources for versions newer than 3.10 or so.
So here's a little link that might be really usefull since it contains:
Dede 3.50.04 build 1625, Dede.310b.complete.src.zip, full html doc, complete dsf directory, DeIDA package, and at last, Dede SDK v1.1.
Beware the zip file is 7.5MB !!!!
Enjoy : hxxp://www.wasm.ru/tools/13/DeDe.zip