DBLAZE, at last I think I found the reason for that clunk. I get the noise when I am around 20 ~ 25 mph and right after I let go the gas pedal, I get the clunk noise. Anyway, it seems like a difficult DIY and the dealer will charge a lot. I was just wondering what happens if you don't fix that? Anyway, the noise is not that noticeable.
I prefer to spend that money somewhere else.