Im not sure how to describe this but a Whining noise sounds like wwhiiieeee) .. not too loud but audibly
Is coming from the front passenger side mostly on 1st gear when need some torque to going up in a hill .
Im 99 % sure is not the tranny
Sounds like when the belt is bad but not that loud

Im flushing differential fluid tomorrow . Just checked the shaft and it is firm . No movement or noise
Btw 3 days ago I got a 4wd service message while I switched to 4x4 low and try to get it back in high . All came to normal after turn off on the truck .

Just to isolated the problem Belt and tensioner replaced . Pulley will be replaced this week .

Fortunately I love this truck as a family member but it is a headache after another and Is turning in a very expensive family member

In the Last 2 months I replace oil pen gasket,mainrear seal , oil pressure switch , starter, the heater hose and Y , the belt , the tensioner, the pulley .

On the good hand I just drove 2000 miles at 85mph and not problems

 

Was the 4x4 problem in TN and COLD? Mine would do that once the temp went below 35º, but only when the truck had sat overnight. Once warmed up and shut off for a few minutes it worked fine. SInce changing the sync motor had had no probs.

My whine was the power steering pump, make sure you eliminate that. And older vehicles are just going to cost money for the upkeep. You've had your truck long enough to know it pretty well, and apparently I won't live long enough to see any CORPORATION come out with something to replace these beasts so they are keepers.

Family member? I've spent untold $1000s on the wife and kids, not to mention in-laws and the odd niece, nephew or uncle. I'm getting off cheap with the Hummers!!

 

Family member? I've spent untold $1000s on the wife and kids, not to mention in-laws and the odd niece, nephew or uncle. I'm getting off cheap with the Hummers!![/QUOTE]
Lol . You are right .

Just replace the pulley . Plus the fluid in both diff which were due anyway
And everything looks good. It is s relief to see the dog fluid clean .
Was leaning to the Alt and the steering pump. But yes 99% the Sp may be the issue .
It is only 70k miles old as it was replaced by the dealer when got the truck .
Is there any aftermarket upgrade available

The Tc Issue was in Tn and yes it was cold on the 30s
Most possible is a dort connection or the motor
Will test again now I'm back home