So, I have been experiencing a thump or clunk in the rear end for a while. I thought for sure it was the carrier bushing. That still might be bad, but I don't think it is causing this problem. If I am driving at about 55 MPH and let off the gas, there is a fast thump and shake the comes from the passenger side rear of the car. So, while in OD this happens. I am thinking it is something inside of the rear axle. Also, there is a thud when I get back on the gas. Anyone have any ideas, or dealt with this problem before?

 

hmmm... I think what I might have is similar. Gives a good thump and then its smooth. Not sure what it is though because it is random and you cannot recreate it.

 

FWIW - and it's unlikely to be the answer.... But I had a bit of a 'thump either slowing down or around some corners - difficult to reproduce whenever desired - and it turned out to be my spare that was not wound 'up' tightly enough. I got the hint through a post in this forum - checked and tightened - and my RX feels tight again. Good luck!

 

Another, FWIW, I experienced a thump sound in the rear passenger side two days ago while driving at 30 mph---came on suddenly and got worse as I depressed the brakes then as I sped up it seemed like I had a rear flat tire.
Drove to my independent mechanic and he drove it for a while before he could reproduce the sounds. Turned out to be the rear caliper on one side was completely destroyed and the other side he said he could rebuild. Not sure if your situation is similar, but you may want to have your rear brakes checked out.