Exporting 3d file

[thighfill]

Will Geopac accept a 3-d AutoCAD 2000 file?

[mjfarrell]

I believe that it will. Their web site says that V8 2004
handles these file types with ease:
Comprehensive R14/2000/2000i/2002/2004 DWG support: Create, edit and reference data in hybrid workflows without translations between formats.

To be safe perhaps try both the
original 3d file, and a DXFOUT of the same data
and compare your results.
Given that this export is to a civil design application,
any chance your data is coming from Land Desktop?
If so why not try an export as LandXML to get your data
into Geopac. Although I heard there are issues with the
file header XML as Bentley choose to violate the XML.ORG
standards for LandXML data, and possibly will require some
editing to function correctly.