2002 Tahoe: rear differential is making a growling noise. I re...

Provided that this is a rear-wheel drive vehicle, there are a number of things which can make noise when you accelerate. Most are due to excess clearance in moving parts. This means some parts are worn out.

On the outside, the U-joint next to the rear differential can be worn and make noise. Inside the differential, usually a pinion bearing(carrier bearing) can make a noise like a whine or growl depending on the gap.

Now in the axle tube, the axle shafts have a bearing on each wheel. Like any bearing, when they wear out, noise usually indicates failure.

When Torque is applied on acceleration, the parts shift creating noise. If you have a Limited Slip Differential, there are clutch plates which have a material which can wear out. These types of rear ends also need a special Additive to make the parts work. Sometimes you get a clatter when the additive is low.

Have the U-joint checked first as it is the only external part to check. The rest will need disassembly.

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never needed a spreader on a tahoe with the axles out put a heavy rag between the gears and rotate the pinion you need to remove it evenly

you would only experience problems from the diff if there was a substantial increase in torque from the different engine as there would be less than 10% difference in torque ratings , Any noise from the diff would be naturally occurring from wear or oil
diff noises indicating bearing problems are a whine on drive or coasting , an growl on deceleration and a harmonic whine or growl when the vehicle is held at steady speed Other than those indications , I would be more inclined to suspect wheel bearings and brake associated noises
wheel bearings are normally more pronounced on cornering

Fisrt thing to check is the differential fluid, make sure it is full up to the plug. If this is dry you could have ruined a bearing in the rear end. Next check all the rear axle bearings. Most likely it is the differential and the gears are dry and when they dry out they scorch and cause a noise like this.
If no issue found in the rear end it may possibly a bearing in the tranny. These noises travel through the steel and sometimes get confusing as to where they originate from.

could be rear axle bearings.

Usually, the rear pinion bearing will make a higher pitched whining noise under a slight load. As soon as the throttle pedal is released, the noise stops. The rear axle shaft bearings will make a lower growling rumble when they are bad.

Another thing to check are the Emergency brakeshoes inside the hub of the rear rotors. The shoe material frequently separates from the rusty shoe plates and the bonded material gets pulverized. This would be similar to a "rocks crushing" sound and can cause vibration in the drivetrain.

The U-joints can cause this problem too. Check for rust and oil streaks which appear shortly before the U-joints fall apart. You should find telltale streaks on the undercarriage of your vehicle.
The front driveshaft can cause noise without being powered. There is just enough sympathetic rotation when the 4 wheel drive is Off, to cause sounds and vibration.

Testing can be aided by using a Commercial hoist and having the drivetrain engaged with the engine running. You would observe the shaking or use a probe "long broom handle" to the stationary parts like the axle tubes, differential housing, pinion bearing area, and so on. This would require a helper to sit in the hoisted vehicle and a second person to stand under a running machine. Not for the faint of heart. No baggy or loose fitting clothes, no long hair, etc.

Now there is a specialized machine which can Electronically investigate noise and vibration. There are sensors which are placed under the vehicle and it listens to vibrations. I saw one machine one time. It helps in balancing driveshafts too. A driveshaft balancing shop may be able to fix you up.

I hope my solutions are very helpful to you. If you do not have the exotic testing equipment you may have to drop the driveshafts to check your U-joints.

Sounds like your rear diff is winding up. possibly rear diff /or transfer box fault .

This could be one of several problems: If the noise increases with speed, and you are only hearing it from the rear differential and not the transmission, it could be the rear differential carrier bearings, or rear axle bearings going bad. If you are only hearing the noise upon acceleration or deceleration, the rear differential ring and/or pinion gears may be going bad and the rear differential will need an overhaul. You'll have to get the rear wheels off the ground and see if you can pinpoint the location of the noise with something such as a stethoscope. If it's coming from the rear differential, you'll need to pull the bolts and the cover to determine if the gears are still in good shape, or if there is any pitting. Same with the carrier bearings; if you see pitting/ discoloration, they'll need replacement. If the noise is coming from one side towards the end of the axle shaft near the wheel, it's most likely a axle bearing going bad, and you'll need to pull the wheels, remove the diff. cover to release the C clip which holds the rear axle in place at the differential, and pull the axle out. You also need a special tool with a slide hammer to remove the axle bearing and seal.

Not that difficult, raise and support the rear of the truck and remove the wheels. Might as well replace both sides so you know you have new seals, remove the differential cover and drain the fluid. Once differential is opened and cleaned , remove the axle "C" clip that hold the axle in place and slide the axle out. Once the axle is out remove the wheel seal and clean around the area. This would be a good time to replace the wheel bearing too since you have access to them and there not that expensive. Install the new bearing and seal, note make sure you oiled the bearing and seal before installing it back and take care when installing the axle back in and "C: clip. Use RTV silicon gasket maker to seal the differential cover and wheels back on and lower. If your lazy like i am, you can drain the differential fluid and replace it with a 50/50 mix with gear oil and Lucas engine oil additives. That may stop the leak and get you a few more miles. You gear oil is 75W-90 and the capacity is 2.6 liters and 3.6 liters if you have the 11.50 Ring gear. Good luck and hope this helps. 

Remove the drums and check your rear brakes. If okay, you may try testing a couple different tires in the rear. Belts separating and flat spots show worse at higher speeds.
It could be bearings if truck is used alot while loaded. Remember 1/4 ton is only 500lbs. High miles, hard driving, or if it was wrecked in rear could all cause these smptoms.