Hi,
On the basics involved I agree with the other posters that it is not the rear end itself.
There is nothing inside the rear end housing that can go out of balance that much and it still work. Bad bearings can create a roar. Nothing "weight wise" could shift out of rotational trajectory and the rear end still be working.
Take a balancing weight that comes off a tire isn't enough with to be noticed on the rear end of the car in lots of cases. The rear end is heavy when compared to components of a front suspension.
It does not compute that the ring gear, it being the largest diameter member in the housing, could be off in ounces to do what a tire can do given its larger diameter.
Going with the driveshaft is the best bet because it is rotation is faster than any component in the differential except the input gear that is very small.
The bearing on it usually has an issue first.
The drive shaft is rotating from two or more planes of direction and the bearings in the joints are taking the brunt of the forces to keep it from whipping around each other forces.
Imagine taking a heavy link chain and swinging it round and around between two people. The center will bulge outward as each link adjusts to where they are standing and the ends will move closer together.
Now, try to hold the two end links in your hands, pointed directional together, timed or in the same phase.
Like your wrists and hands they will feel the torque because the cars load will not moving instantly proportionally. A drive shaft is stiff and rotational torque is going to get supplied. Those bearings in the U-joints or like your knuckles in your fingers.
It's amazing they last as long as the do.
It helps that they rotate or pivot better than knuckles do.
If it wasn't for Computer Numerical Controlled Grinding machines you would not see front wheel drive cars, on the road in their great numbers without the CV- "steering" Joints lasting as long as they do. CNC made them affordable as they are very complex part when compared to a four point Universal -Joint.
I have never owned one of those bears and hope I never do. I like my turning radius.
I sure have heard them popping and crackling between 80k to 150k depending chiefly on teenagers and horsepower.
Now if the rear end, is not held firmly in its mounting bushings, that could be another story all together. Give them a good look over all for support strength.
Phil
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