There is nothing in the 1999 Annual report that makes specific mention of the 736. In the fleet section, it mentions that Delta has 267 "rolling options" for 737-600/700/800. In another section, it mentions that Delta has negotiated industry leading pay rates for its 737-600/700/800 pilots. There is nothing specific about the -600, however the fact that it does make some mention of it is a little fishy.
Contrast that with AA and Continental who make no mention of the 736 at all in their reports, and you can see a pattern developing.
But why would Delta Express want new planes for itself. DL could just shift all its current 733's to Express and keep the new 736 for itself.
Agreed that the 717 is perfect but NW....but why aren't they ordering it?
Now would be the time since the 717 is cheap and revenue is rolling in.