Well, there is an easy test for the internal shift linkage/rooster tail.
Start the explorer then when the idle is stable, attempt to put it in gear. IF the RPMs drop (like it went into gear) then the external shifter is connected to the internal shifter/rooster tail.
If it starts "in gear", in other words you move the shifter on the column and the rpms don't drop (meaning it was already in gear, but the parking parwl was engaged) then the external shifter isn't connected to the internal shifter.
If they aren't connected, you can drop the pan and you will most likely see the internal shift rod just lying there and not connected to the rooster tail...
If they are connected, it's time to take it in as I doubt there is much you can do at home...
~Mark