The solution for this may be VERY simple. I had James (inarush) do a full DTT setup on my transmission a couple of months ago, and I told him about it. When he was under the truck he noticed that there is a little plastic "guide" that is clipped into the floorboard and it had came loose. Just a simple little click back into place, the noise is gone!
Check that item. its accessable from under the truck, and I'm sure you could get it from inside the truck if you wanted to pull everything out of the way.
Corey