Took the driveshaft out and replaced u-joints and carrier bearing. Balanced and replaced. I've replaced the seal 3 times now due to leaking, this is all within about 4000 miles. Talking to my mechanic he thinks it might be a brass bushing inside the tail shaft of the transfer case. It's not leaving a puddle under the truck, but it's sure flinging fluid on the bottom of the truck. It's on the 2011, with about 240k...