If you have a valid license, the Autodesk Account page often hosts "Extension" packs. Autodesk frequently releases subassemblies designed for specific regional standards.
Professional groups like "Civil 3D User Group" frequently post resources. Civil 3d Subassembly Pkt- Download
: You can actually "extract" PKT files from your installed Country Kits . Navigate to C:\ProgramData\Autodesk\C3D 20xx\enu\Imported Tools , zip the contents of a subassembly folder, and rename that .zip to .pkt to open it in SAC. If you have a valid license, the Autodesk
: Right-clicking the palette and selecting "Import Subassemblies" to browse for the .pkt file. If you have a valid license
Before clicking "Download," check the Version compatibility.