As stated previously, by ProjectDShft and others, all the Nissan/Infinity/Datsun Manuals can be found here:
How To Use NICOclub.com
As a new Z owner I just ran across this thread and have discovered a few things that aren't covered yet so though I'd share.
If you use Firefox, you can grab an AddOn called DownThemAll. It's very well rated and works amazingly well.
Install the AddOn, go to the appropriate Nico page with the pdf listings for your model/year, go to tools (hit alt if menu is hidden) select DownThemAll.
Once the dialog comes up, you'll see a list of files. At the bottom, drop down fast filter and type in pdf.
DTA1.jpg
This will limit to only pdf files on a page.
DTA2.jpg
Select a download location and hit go. Fast and easy it pulls them all down.
Lastly, and perhaps most importantly, note there is a fwd.pdf included. It's the manual index and is referenced on the main NICO page above with a little how-to. I renamed this to 0-Index.pdf so it would always be the first file in the list.
What it doesn't say is if you open the index page with Adobe Reader, as long as the remaining files are in the same directory, you can click on an item in the index and it will jump to the appropriate sub file (sub manual).
This takes the guess work and trial/error out of picking which sub manual you're after. The names aren't real clear with GI, GW, HA, HAC, HRN, etc.
Best of luck. Hope this helps someone else stumbling in.