Ok so we fixed one problem but still have more. Ford does use vacuum set up to engage the front diff. Now the old motor may have shorted and taken out another components. Ok all that is left is the buttons and the GEM Module that controls all that kind of stuff and more. Do you have any way to pull codes from the gem? It is a different scanner then the OBD2 scanner. Here is the vacuum diagram for the front diff. Now keep in mind that the GEM controls all this when it know's the transfer case is engaged so check the vacuum lines and routing and make sure there are no leaks or broken lines if not then we will have to check the GEM. If you have access to an NGS (Next generation scan tester) this will make it a lot easier to check it. Let me know where you would like to go from here.
