04 Sierra Transfer Case replaced 5 times

[ironhorse2004]

Help, I have a 04 GMC Sierra, 4x4, 6.0 gas and I need some help.  I will be on transfer case number 5 and cannot figure out why?  Originally the first one went out.  I got the first one and it needed to be replaced due to the rear seal for the rear driveline was installed wrong.  Got the second one and the shift motor went bad and then they sent me a new shift motor and then it started vibrating when on the highway.  Went with a different company/manufacture and the same thing has happen.  I have had it start vibrating, leaking, etc.  I am now looking at TK#5.  I have had new U-joints replaced on both ends and had drive line balanced.  Any help on where to go from here before I put in number 5 would be greatly appreciated??  What would cause this?  Front end seems to disengage when it is jacked in the air, gas mileage has never changed?  Help!

[Jsdirt]

What are you running for lubrication?

 

And, why was #1 replaced for just a tail shaft seal?

 

A new shift motor, even if installed wrong shouldn't cause a vibration, unless it got caught between gears and broke something.

 

Transfer cases are usually one of the more bulletproof items on a truck, even today. Not really sure what you've got going on here. Could just be a run of bad suppliers.  

 

Are these new, remanufactured, or used units you're installing?

[newdude]

What shape is the rear transmission mount in?  Is the extension housing cracked/warped/damaged? 

[ironhorse2004]

Running Auto Trak II Fluid as specified???

#1 was replaced by remanufactured company due to oil leaking out.  

 

You are correct on shift motor, I chalked that one up as bad luck.  After the shift motor went out and replaced it is then the TCase started vibration

 

All have been remanufactured.  Very frustrating.

 

As far as the rear transmission mount I have them all done in the shop with the exception of the first Tcase.  I did the first one and everything past that has been warrantied with the exception of #3 when I was two hours from home and it went out.  I had to pay for the labor on that one.

 

I hate to put another in without knowing what is going on so any help is very appreciated.....