[trogggy]

When I originally setup MySQL and my Kodi sources I setup shared drives to my Unraid servers. So everything in Kodi and MySQL all point to drives Z: and Y:.  The Nvidia Shield has no clue what Z and Y are or how to reach them and I assume there is no way to actually map drives to letters on that OS.

As I understand it the 'proper' way would be to have the same sources on each machine - ie use a network source rather than local on your pc.
But in my experience using path substitutions in advancedsettings.xml works perfectly.
Assuming you can actually see drives Y and Z from your shield (by whatever means - smb / nfs / ftp / etc) it's just a case of adding the right lines to your advanced settings.  Have a look in the wiki for details.
So something like:

        <pathsubstitution>
            <substitute>
            <from>Y:\whatchemacallit</from> (whatever's in your sources.xml)
            <to>smb://192.168.x.x/thingy/whatchemacallit</to>  (the actual path to the folder from the shield)
            </substitute>        
            <substitute>
            <from>Z:\thingumajig</from>
            <to>smb://192.168.x.x/wotsit/thingumajig</to>
            </substitute>
        </pathsubstitution>