[BarryGMC]

Before you take it out put the t case in neutral and try to recreate the sounds. Take a 3/8 dowel about two feet long. Have someone run the truck and while they run it listen to the trans all over . You use the dowel as a listening stick. Put one end in your ear and the other end at the point you want to listen to. Now don't laugh you will be amazed at what you hear. You can practice on your valve train . Move along the valve covers. Listen and compare areas. Every rig I buy that runs gets the stick treatment. I have two one is about two feet and the other is about 5. I actually jack up the driving axels and run it and listen to everything, front to back. You would be amazed with a little practice how you can identify a failing or failed bearing and locate it.