I have a 2015 chevy colorado. At 6000 miles I could hear a whining or howling noise I thought it was coming from the trans or rear end. I have taken it to glendora chevrolet 4 times, and no one can hear the noise but me. My two adult sons can hear it, my wife can hear the noise. I give up!!
Time to try a DIFFERENT shop.
How is it that you only have 6 thousand miles on a 6 year old truck?
Has your shop double checked both the trans and rear axle are properly filled? Are you certain the sound is coming from underneath the car, and not some sort of surface wind sound? Have you added anything that would modify the airflow over the surface of the truck, like a rack or something?
If you agree to pay a mechanic for their time, they’ll be happy to disassemble the rear axel for a look-see at the pinion to ring gear alignment, and measure the backlash.
That is exactly what I was thinking, but I’m also wondering why the OP is taking this truck to the dealership after the warranties have expired on the basis of elapsed time.
Not 6,000 it’s 60,000
If you gave up,why are you here?
I have the same vehicle and had the same issue around 120,000. Took it to a shop and I ended up needing new bearings in the rear diff. Was about $1300 all in.