Need 4x4 Help

[Vince13]

I have a 2005 Duramax 2500 HD 4x4 with a 160,000 miles on it.
We just had our first snowfall here and when I popped her into 4HI it really feels like she is dragging. It is hard to explain but it's like the rear diff is a different ratio compared to the front diff. The steering is darty and jumpy and you really have to apply the power to get her to move.

As soon as you go back to 2HI it is nice a smooth and steers normal. It is not coming out of 4hi smoothly either one time there was a big thunk you could feel and hear. 4hi is working though.

I changed fluids in the transfer case and front diff and the problem is still there.
Any suggestions?

Thanks

 

[pdzz]

Might sound stupid, but, how's the tires? Size? Worn out in the rear? That mileage, could be bearings binding in the front diff, hard to say without actually seeing it. Phil.

 

[Vince13]

Same winter tires I have run for 3 winters, I rotate them and the wear is pretty even. Replaced both front hubs due to worn bearings in the last 2 years. It used to be silky smooth shifting from 2HI to 4HI but now it is like dropping an anchor and it will not easily come out of 4HI. Sometimes I have to stop and reverse to get it out of 4HI

 

[pdzz]

Sounds like something in the transfer case.

 

[Venus]

I would suspect a Front Differential.....GM trucks are known to have issues with them.