I suggest ordering the part & when it comes in, take a look at it & see how it attaches. Then take the door panel off, remove the broken vent, install the new one, put the door panel on again & you'll be set!

 

Take a look at this diagram on the Courtesy site:

http://www.courtesyparts.com/350z-pa...5_846_857.html

It looks like it's not installed with any particular bolt, so it may be held in by tension only.

 

i had this problem just yeserday.... remove the rubber piece thats on the outside frame of the door.. if you look inside theres a screw in the center holding it in place use a phillips head screw driver to hold it in place so you can unscrew the vent counter clockwise.. take it out and put the clip back onto there and put it back and ur done

 

Took about the same time to remove & install the new vent as it did to turn on the computer and type this reply! BRAVO!!