Calling All Mechanics on GLP......I need some gawt-dayum guidance

Ok, I'll lay out the facts

97 Tahoe 2 door Z71 Sport with all the off-road goodies offered by GM

Now, the rear-end/differential is making a whine/hum that starts around 20-25mph and is constant all the way up to 70-75mph.

If I let off the gas it disappears.

The rear end is a 10-bolt 8.6" gear. It has 30 spline axles, it has the factory G80 locker and 3.42 gear ratio.

I replaced the axle bearings/seals and changed out the differential oil and added some reaally good friction modifier for the locker.

So, this is my question. Is this pinion bearings, carrier bearings?

Is this the backlash on my gesr and pinion becoming too sloppy?

If that's the case that means my gears are fucked, yes?

Anyone can share their .02 cents as long as it's constructive and on topic.


I have Chevy's, Ford's, Dodge's, and Toyota's in my driveway so nobody needs to say I need to get rid of my Chevy.

All brands have their pluses and minues. So no shit talking about what brand is best. I have all the brands worth owning and they all have issues....even my 97 'Yota FJ80.

I just want to know how fucked I am with my rear differential. I've never rebuilt a rear differential before so diagnosing this whine/hum has been hard.