I'm noticing a gentle rear end "clunk" (multiple) at very low speed--parking lot speed-- coming from what sounds like the undifferentiated rear of the car. It doesn't seem to be related to pavement or surface issues, and doesn't seem to impair the roll of the car. It basically happens when I idle thru the flat pavement of the parking garage at about 8 mph on the 5AT, and at other LOW speeds. It goes away (or seems to) as speed increases. It also seems to diminish with a full tank of gas. My 2004 Roadster is stock except for Stillen sways w/ Prothane bushings and nismo exhaust.
Can U help?

 

I'm not sure if this applies to the rear, but I know there were other members who said they experienced a similar clunk in the front which was caused by bad end links. I have the exact same problem (G35 Sedan) in the front. I'm changing my front end links to the heim joint NISMO S-Tune tomorrow. Hopefully the noise goes away.

 

there is a tsb for the clunking you are hearing. it deals with the rear axle not being lubed up properly i believe. the dealership took care of the problem for me a while ago (a year or more ago) and it has since not been a problem.