Don't spend money on Haynes, they are not that great. Try Google 350z service manual, there are pdf documents out there that you can download for free. I find it much better compared to Haynes.
Edit: Here's the link to download the OEM service manuals http://www.nicoclub.com/FSM/350Z/coupe/2004_Coupe+Roadster/ You'll need to look at specific copy for what you need