As a level 4 Jeep Driveline tech I feel the need to chime in on this one. First off the NTH (noise vibration and harshness) sounds like one of 3 possible issues. First check the trans mount for tears or a soft/squishy feel to the rubber...if the rubber is not "hard" replace the mount. Jack the rear end up on the pumpkin and set a jackstand on each axle tube and support the vehicle on the stands...spin the drive shaft and see if it binds...if it does you need to install a SYE and CV shaft ...if it doesn't bind then your input bearing is bad in trans. Check the driveline for binding and/or severe driveline angles.