2007 Silverado 2500HD Classic screeching/squealing noise in first gear

[tperkins]

I have a 2007 2500HD Classic with 146k miles that I've owned for the last 2,500 miles. It makes a sound when accelerating in first gear that I would describe as a screeching or squealing. It builds in volume as RPMs rise and then quickly drops off after the transmission shifts to second. The trans shifts fine, fluid is good, normal high temp stays within a range of 150-170, no problems to report other than the noise.

 

I've read that the 4L80E planetary gears can make a decent amount of noise, but as this is my first GM truck, I'm not sure if what I'm hearing is within the normal range or not, or if this is another issue entirely.

 

Any help would be greatly appreciated. Thanks!

 

Video with audio of noise:

 

 

[Formulabruce]

Transfer case has a spot that wears due to a smaller than should be shim. I would see about getting a vacuum hose on a T case bolt end and listening to it while ya drive.. good luck,.