If it only happens when you are decelerating and goes away when applying the clutch, that is gear rattle in the transfer case adapter, which is very common. If you didn't have it before, you could possibly have a broken driver side motor mount or even a broken t-case mount.
Thanks to Nikki and Cacy for letting me keep the 4Runner at their house throughout the Gilligan Islandesq renuild of my trans. And to Cacy for all thee help/suprivision in keeping me from breaking anything else while fixing it.
Thanks to Marlin for helping me out with that rebuild.
Thanks to Talon for helping with pulling and reinstalling it and Thanks to Mike for doing the heavy lifting and putting it back in.