Identifying the Project number associated with a General Ledger journal line

We have auditors visitng that request we provide the project number associated with the journal lines interfaced and posted in the GL.  While it is possible to see the project number in GL for one line item  using the Line Drilldown button while in the JE lines, we need to know the project table names from which the Drilldown data is pulled.  We've created a GL Journal Source script to provide the auditors with the GL activity but we're missing the project number reference.  I didn't find anything useful in the gl_import_reference table.  I was hoping for a project_id reference.  Can anyone assist