Sounds like something is off balance

neither a bent driveshaft, nor out of balance tires, nor tires with blown cords or out of round... make noise, they just shake.
Axle bearings and rear ends make noise..... but usually don't shake.
But when the bearing gets to a certain point, be it a tapered bearing out of adjustment, or a green-bearing type worn, then the brake-drum and shoes get involved. This is an easy find, just jack up the the rear end and test for vertical play at the wheel. and of course rotate it; noisy wheel bearings are obvious.
A bad pinion bearing will make noise as the pinion moves back and rubs on the case and the pattern goes away.It also allows the spinning driveshaft to vibrate.
Bad side bearings are just noisy, but in my experience this doesn't happen very often. If they went bad I suppose it could be accompanied by vibration.
A bad pinion angle will cause a subtle hard to find vibration, but not usually accompanied by noise.
Two different diameter rear tires will cause the side-gears to rotate at different speeds. This heats the oil and soon the crosspin wants to seize to the spiders. In the meantime this does make noise, AND vibration as time goes by.
Good luck in your search