I have a 2003 excursion with the V10. at the hunting camp I drove it into some water without knowing my neighbor had gotten stuck and left a BIG hole. It took an hour to pull it out with a tractor. The water was up to the floor boards. afterward the transmission would not shift past second. The OD light blinks. I left it for two days to dry out. Still no good.

Any suggestions on what I need to do to get it back going?

 

As you know when you cool something that was hot the internal pressure drops and creates a vacuum. That is exactly what happened to both of your differentials (if 4 WD)
your transfer case, and your transmission. The less you run it before draining and refilling the better.Chances are pretty good they are all full of water. After that is done , remove each plug with electrical wires and make sure they have no water/moisture in them to mess with the contacts. WD 40 works well for this. As far as the transfer case and trans are concerned if you operated the vehicle with water in the systems you might cosider changing the fluid and filter again because some of the contaminated fluid has been sent into the clutch packs and valve body and another fluid and filter change should allow more of the soup to be removed.