2005 Jeep Grand Cherokee High Pitch Noise Vehicle Accerating Sustaining Speeds

Does it sound like it is a belt?

check belt tension and inspect engine for intake vac leaks.

could be a pinion bearing. is this Jeep a 4X4?

gear noise could be the problem. how loud is it. does it only do it in high/final gear? is it manual trans? they tend to be noisy.

It ix 4x4. I was guessing pinion bear. Just trying to confirm.. sorry i should have been more specific about noise. Noise is coming from rear of vehicle. Am not sure if it is drive line, differential, or rear bearings.

did it just start? or has it got worse? i've seen people drive noisy gears for years. your may be what's called a rear end howl, of course at that volume, the misaligment/wear is severe. usually a model of vehicle is famous for certain noises and bad parts resulting.

The noise started at 25,000 mile and has gotten prgressively worse. We took the vehilce to the deal back then but they said there was nothing wrong. Now the pitch is so high that it hurt the ears. I dont think that it would have been cover by warrantee because the defect can be tied to uneven tire ware.

with park brake engaged and transmission in park (if automatic) or any gear if manual; try turning the drive shaft by hand to check for play in the pinion bearing. If there is a fair amount of play then suspect the bearing and race needs to be replaced.