Alright my 04.5 has a constant whine noise that I just can't put my finger on. After a little investigating the first thing I did was take the front drive shaft out and drive it in 2WD and just like that, no noise so naturally you would think replace the three u joints on the front drive shaft and problem solved. I did that, reinstalled and the noise is back . I am now offically stumped...I never ran the truck in 4WD when the driveshaft was out so i'm going to try that tomorow. If it makes the noise then I would assume it is in the transfer case. Any thoughts or ideas on this willd be appreciated!!!

 

even locking it in with the front drive line out the front axle is going to still lock in im not sure if they run off vacum or electric anymore but i would unhook the front accuator and lock it in and then hook it back up and lock it in to check the frontend

 

Transfer case won't make noise without the front drive shaft in. Mine case was shot, pulled the drive shaft, put it in 4wd and drove around, didn't make a sound. Have you checked the fluid in the case, diffs, etc?

 

Turns out it was the outer pinion bearing. What a project...both axles and the third member came out. I had to install a race, crush sleeve and seal. While I was at it I did the two u joints on the axles also.

 

That sucks, but at least you found out what it was. Plus it gave you a good excuse to replace the U joints and new racing. And now that whine is gone!