DynamicsCRM Data Export Service---Determining Entity Key Column

Is there a way that we can determine the Key Column(s) used in our current DynamicsCRM Data Export Service?

We are in the process of trying to replace the Deprecated Data Export Service with a SSIS Solution using Kingsway components and in order to use the UPSERT we need to identify the current Entity key column(s). 

Is there any way we can determine those key column(s) from the current existing and running Data Export Service?

Thanks for your review and am hopeful for a reply.

ITBobbyP85