Auto trans stumper

Is this the same overrunning clutch that makes things go boom? That thought did cross my mind when I was under the truck and the wife was shifting it.

Yes it is, but it requires some pretty fair RPM's to explode.
The sound you are hearing may be the pressure regulator valve "buzzing" and that can be caused by a plugging up filter. (one of the reasons)

You may want to pull the pan as suggested and post a pic of the pan contents.
Then we can assist in the rear band and servo inspection while you are in there.