I have a customer who has an earlier version of AutoCAD. I need to give them a version of the project they can use. What are my options?
If you select your Application Icon and select Saveas or type Saveas.
When the Saveas Dialog opens you will notice at the bottom a drop down called Files of Type. Select this drop down and then you can select earlier versions or DXF versions. Note that the AutoCAD file format traditionally follows 3 releases. So 2007 is for 2007, 2008, and 2009. 2004 is for 2004, 2005, 2006. Also if you are using a vertical product such as Civil 3D these are not standard formats and you should use. Export to AutoCAD to take the vertical data and convert it to standard AutoCAD data.
AutoCAD Civil 3D 2010 - Application Icon->Export->AutoCAD->Version
AutoCAD Architecture 2010 - Application Icon->Export->AutoCAD->Version
Autodesk Revit 2010 - Application Icon->Export->CAD Formats->DWG