Wheel balance, tired shock absorbers or a bad tire due to belt separation.
check the rear drag links for wear the ball joints wear out a lot on them
More than likely the sway bar links - TSB on these
Could be universal joint is finished. A bad flex disk
Have that tire checked sometimes the belts inside can break and cause a thumping noise
A rear tire out of balance.
Maybe that thumping noise is the sound of another car smashing into the rear of your car.
You created a flat spot on the rear tires. Your car had a busted mount or bushing
i don't know if this helps but i just had my car repaired tonight and when i picked it up this was a new problem that wasn't there before. i took it back and they said the thumping was caused by a rotor??? that they forgot to tighten? i am not sure i have the name right!
worn torsen differential
Bad shocks or struts is one possibility.
My Dodge Ram 1500 is in the shop right now for the same thing. They are telling me its the rear differential.
tire or wheel out of balance? broken mount on rear of transmission. I have seen where the threads for the bolts into the trans are ripped out.