Sorry but you don't count properly. 🙂 2006 is earlier, not later, than 2007. See below:
Mac Os X Lion Dmg
Jul 23, 2012 As we’ve mentioned in the past, the Mac Pro has not received a major design update since the chassis belonged to the Power Mac G5 in 2003. Jabbawok has one of the first Mac Pros from 2006, and has found a way to coax Mac OS X 10.8 Mountain Lion onto the aging professional rig. Jul 26, 2012 Click More Info to get detailed information about your Mac. Here you can see I have a Mac Mini Mid 2010 with an Intel Core 2 Duo CPU, 8GB of RAM and OS X Lion 10.7.4 (11E23).
Upgrading to Mavericks
You can upgrade to Mavericks from Lion or directly from Snow Leopard. Mavericks can be downloaded from the Mac App Store for FREE.
Upgrading to Mavericks
To upgrade to Mavericks you must have Snow Leopard 10.6.8 or Lion installed. Download Mavericks from the App Store. Sign in using your Apple ID. Mavericks is free. The file is quite large, over 5 GBs, so allow some time to download. It would be preferable to use Ethernet because it is nearly four times faster than wireless.
Os X Lion For Mac Pro Late 2006 Specs
Macs that can be upgraded to OS X Mavericks
1. iMac (Mid 2007 or newer) - Model Identifier 7,1 or later
2. MacBook (Late 2008 Aluminum, or Early 2009 or newer) - Model Identifier 5,1 or later
3. MacBook Pro (Mid/Late 2007 or newer) - Model Identifier 3,1 or later
4. MacBook Air (Late 2008 or newer) - Model Identifier 2,1 or later
5. Mac mini (Early 2009 or newer) - Model Identifier 3,1 or later
6. Mac Pro (Early 2008 or newer) - Model Identifier 3,1 or later
7. Xserve (Early 2009) - Model Identifier 3,1 or later
To find the model identifier open System Profiler in the Utilities folder. It's displayed in the panel on the right.