The manuals are included with the help for Microsoft Dynamics GP. They are located in Help-Printable Manuals.
Each area listed can have multiple manuals. All the manuals are in PDF format and they commonly run a couple of hundred pages each. That's one reason why you don't get a printed set of manuals. The other reason is that too many people never read them and it's expensive to print stuff that no one reads.. I was a at a long time client recently. They are on GP 2010 and had recently cleaned out old filing cabinet. They found GP 6.0 manuals still wrapped in plastic never opened.
The included printable manuals are searchable and do a great job with the what and how. Sometimes they fall down on the why. If you're looking for help beyond the manuals, I highly recommend the Microsoft Dynamics GP 2010 Cookbook of course.