I had more of a rattle than clunk coming from a vent behind the bumper cover. It clips in on either side but one of the clips had come loose due to the weather stripping coming off.
Access is from the inside of the hatch after removing interior molding.
https://i.imgur.com/lxQHb34.jpg

Hard to solve this issue over the internet. I would have to drive your car and feel what it was doing to be of any further help.

This is exactly the kind of intel I was looking for. I'll check this.

Agreed. Thanks for the ideas. The diagram posted with a suggestion to check an internal vent clip is exactly what I was hoping someone would offer up. I'll be checking that this weekend.

Took the interior panels out to access this vent mentioned above. My vent is tight and no rattles here.
I’ve been searching the depths of the forum and have read in a couple threads about the upper shock mount being a potential culprit. Going to check that next.
Thinking about removing both rear shocks and low speed driving around my neighborhood just for process of elimination.

Problem solved. Removed drivers rear shock into inspect upper mount and then reinstalled. After reinstalling the noise I was hearing is gone. Must have been a slightly loose bolt on that shock mount. Thanks for all the suggestions!

Woohoo, good job! Happy for you as if I removed an annoying clunk on my own car :happydance:

Feels like every other 370z owner has experienced annoying rear clunk at some point lol. Worst of all, the clunking sounds can come from all sorts of different places.