Hi Things, did you figure it out what it was and did you do anything special to rectify the leak? I have a noise that sounds pretty nasty and I've been struggling trying to figure out what it is. I've checked the u-joints, drive shaft boots and various other things underneath and have come up with nothing, except I notice some condensation and some very black soot at two points around the spacer. My noise is harsher than yours it sounds like, but is only when the jeep is under slight flex like slight turns, dips, and things when on the road. I'm guessing that under the slight flex, it's separating ever so slightly and vibrating against each other making the noise. It's very intermittent and very difficult to determine if it's in the front or back, but I'm thinking that's because it's directly below the driver and mostly what I hear is it bouncing off the front/rear areas.
When I get home tonight, I'm going to take that section apart and see if I can get it tighter to see if the noise goes away. The other thing I thought I'd try is attaching the go pro down there to see if a recording helps at all.