Help! Axle Whine...

[JakeZ71]

So... I have an issue with whining. It's bearable when the dog does it, it's bad when the girlfriend does it, but now the truck is doing it too!!

Here's the story:
There is a whine coming from the truck at speed. It doesn't seem to be affected by whether I'm on the throttle or not, but it does increase in intensity when the speed increases, whether coasting down hill or getting on the skinny pedal. It's definitely a whine, not a clunk. Sounds like a bearing? Anyways, it only becomes apparent above 20 mph, so it's hard to diagnose in the the drive way. I know it's not a front axle wheel bearing, but beyond that i'm at a lose. Does any one have any suggestions for what it might be?
I'm hoping rear wheel bearing, but fearing pinion bearing.

Is there anything I'm over looking?

Truck is a '98 K1500 with 161k miles. 5.7l, 4l60e, np243, and what i believe to be a 10 bolt with 3.73 gears, no posi.

Thanks in advance, guys.

 

[90halfton]

A 10 bolt with 161k miles? Consider yourself lucky you made it this far.

 

[aaronb]

Id check the u joints, have they been replaced?
Check for play at the pinion to, and is the pinion seal leaking?
Check the fluid level in the diff.

 

[Biggershaft96]

Another thing you can do is pull the drums off and check for up and down play on the axle shafts. Or throw it op on jack stands and have a buddy put it in drive while you check for noises.

 

[RichLo]

Check rear end fluid level right away! If its low, throw a couple banana peels in there and top off with lucas oil stabilizer and see if it goes away.

 

[Biggershaft96]

Check rear end fluid level right away! If its low, throw a couple banana peels in there and top off with lucas oil stabilizer and see if it goes away.

Banana peels? Old school trick or something?

 

[RichLo]

yep. it actually works pretty well too

 

[RichLo]

check out this thread....

http://www.jalopyjournal.com/forum/threads/sawdust-in-the-diff.352740/

lot of good advice from bannana peels, to sawdust, to ground beef, to pepper and egg whites and more!!!

 

[90halfton]

I put mine in drive on jack stands and put large prying type screwdriver on my ear and against different parts of the diffy when I found that my ring gear carrier bearings were shot, at 100k

 

[Ironhead]

It is not that unusual for the rear end to make a whining noise, as long as it is not too loud, I'd just make sure there's enough fluid, and drive the truck.