Help diagnosing mystery noise

[CaliSteve]

Hi All,
I have a very high frequency noise coming from the back of the jeep. I don't hear real high frequency noises but the wife has excellent hearing and it drives her nuts. Others have heard it also, I can drive the jeep around all day on short trips and no issue, once I put some continuous miles and constant driving it appears. It only makes noise when I am moving, starts at about 5 mph the more speed the louder it gets. I was thinking perhaps a brake issue, still happens while dragging the brakes. New rotors and pads a year ago, by the dealer I purchased the jeep from. The jeep has been re-geared, new axles installed so the running gear is all new, including SYE and drive shaft. Had the noise before the work was done. The wife describes the sound as the squeal you make deflating a balloon when pinching the opening as the air comes out. I don't want to just start replacing parts but have been chasing this for quite some time. Have taken the front drive shaft out and no help, have not driven it with the rear shaft removed.
Any input would be helpful

 

[bobthetj03]

What you're describing sounds familiar to angry sparrows from the centering yoke of double cardan joint on the drive shaft, but since you've removed the front ds and the noise still exists, I'd suggest removing the rear ds to rule that out.

 

[Chris]

X2 to the above. Remove the rear driveshaft to rule it out first off.

 

[CaliSteve]

The rear driveshaft is new, installed last year along with the SYE, but as you say, need to rule it out.
Will do.

 

[CaliSteve]

I removed the rear drive shaft and did 30 miles on the freeway, noise is still present but she says it sounds a bit different, probably due to no drive shaft, since the SYE is newly installed am leaning towards the rear pinion area, all the gears and axles in the rear are new and the noise was there prior to the gears. I know there is a seal, is there a bearing also?