Wow, thanks for the additional info, awood. With the inner door panel off, the speaker/speaker housing off, window motor out, and the plastic liner partially peeled back, I can see the rivets on the window trolley, as well as the rivets on the bottom of the track. Haven't looked for the three motor bracket rivets or the two track nuts at the top of the track.
I can definitely see that one of the cables going to my regulator is broken. I assume it is the cable for raising the window--I can't see where it attaches, but I can see that there is a cable still attached to the bottom of the trolley, which still runs to the regulator. By process of elimination, I figure it is the upper cable responsible for raising the window which is broken.
I'm trying to paint a mental picture of the cable routing in my mind, but am struggling a bit. I'm sure it would probably be clearer if I pulled the regulator out and could study it, but I'm out of time for now...
I'm probably looking at the vice grips solution as well for now, just so I can lock my vehicle ;-)
I did read where some folks might have been able to replace the cables with bike/bicycle brake cable in this thread:
http://www.explorerforum.com/forums/showthread.php?t=87139
Seems like you still have to remove the regulator to do this.
By the way, is there any spring tension on the rear regulator assembly to be wary of? Seems like I've read about that, but I haven't seen anything yet in my situation--maybe it was for the front windows only...