3kish rpm hum/vibration... Transfer Case output bearing?

This has been an issue ever since I bought the truck. It was very subtle at first but it's gotten really bad. When I first got the truck I took it to a good friend of mine who owns a mechanic shop. He put my truck on a lift, put it in 2nd gear and got it up the 3k rpm. He said the hum was coming from the transfer case, specifically the output shaft. We checked the u-joint but it was fine. Has anyone else had this problem and is there anything else that it could be?

 

I have the exact same thing, right around 3K it hums anything above or below and it's fine. I have had it since I got my truck also. Never found out what it was, had it for over a year and never had a problem just got use to it I guess lol.

 

My T case output seal leaked and i replaced it. But never had that issue your talking about.

did you check the Carrier bearing too?

 

I replaced all that stuff, but it never solved it. I don't know what is it, chased it and chased it, never found it. Doesn't seem like it's hurting anything whatever it is. I have just gotten used to it now