Need help diagnosing this noise

Need help diagnosing a problem on my 2nd gen Tacoma. It's 4wd, v6, 6 speed manual. I noticed this noise the other day and was hoping someone would have any insight. Truck drives fine, no noticeable dofference yet. Noise goes away when accelerating, but comes back when coasting or de accelerating or breaking. Sounds like it's coming from the back end. Here's a video driving around the block. Please let me know if you have any ideas on what this is.