I have an 07 Sahara 6 speed, 3:21, limited slip. I've had a thunk in the rear end at take off (sometimes) since about 37,000 miles. I now have just over 180,000. The other day it thunked as usual and then making a turn it had a new thunk and it felt like something moved in the rear end. I drove it a little further and on every turn something feels like it moves from one side to the other and back again at the next turn. It also feels like the rear end is shifting from side to side. Checked everything underneath. All the bushings are good and everything is tight. The drive shaft looks good and has almost no play. Jacked it up and moved the tires forward and back and there seems to be a little noise from the transfer case. Don't know if this is normal or not. Doesn't seem to be any noise from the rear end. Any ideas on what this might be?