I own a 1999 jeep cherokee i actually just bought it and there is a noise coming from what i thought was the rear end i changed the spider gears but the noise is still there. i only make it when the jeep is at cruising speed when its under power its fine. any ideas

 

pinion bearing

 

Could be a bent wheel/wheel out of balance,It can be a pinion bearing a axle seal or even the u joints.

 

What kind of noise? Whining, clicking, grinding?

 

The last noise I had from the rear end was too much chili.

 

It's a grinding noise. I have replace both wheel bearings and u joints pinion bearing seems to be fine. wheels run true and the tires are brand new

 

Pinion bearing.
Wasted a lot of time and effort because I didn't want accept that result. Mine really started howling about 40mph. Not that noticeable below that. Did it myself and it came out fine but you might want to go to a reputable shop.

 

Hey guys I have replaced my transfer case with a used one and I think it made it worse. Now there's a bad vibration at 15 mph through 35 mph. Very frustrated