Have you taken a look at the free AutoCAD converter from SolidWorks Corp called DWGgateway?

Product Description
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No need to upgrade to the next version of AutoCAD® software
You do not have to upgrade your AutoCAD license to the new version of AutoCAD to be compatible with your DWG files.

Open and edit any DWG file using any version of AutoCAD
Eliminate the need to upgrade AutoCAD licenses just to be able to share work and collaborate with other AutoCAD users. DWGgateway™ is the first free data translation plug-in that lets AutoCAD users work easily with DWG files created by any version of AutoCAD software.

Create industry standard PDF documents from within AutoCAD
DWGgateway enables AutoCAD users to create PDF documents that can be shared with virtually anyone. DWGgateway includes Adobe® PDF Library technology. Adobe PDF is the de facto standard for electronic document exchange. More than one half-billion copies of its companion software, Adobe® Reader®, have been distributed worldwide, and the world's top 10 PC makers ship their systems with the application.

Website: http://www.dwggateway.com/

Good luck!
3DCADTips Help Desk