One thing that causes gear whine is when the installer sets the gears up, with the teeth messing a little closer together for additional strength. 
found it here (I know...):
http://www.ls1.com/forums/archive/index.php/t-419169.html
Chris
found it here (I know...):
http://www.ls1.com/forums/archive/index.php/t-419169.html
Chris