The bike is gone, but I realized I still had the SW-Motech Alu-Rack and univeral adapter for a Coocase top box sitting in my garage. These were only on the bike for a few hundred miles. I bought both from Twisted Throttle last year. They no longer carry the Alu-Rack (probably because of the $185 price tag), but they still have the Coocase adaptor plate for $35. The Alu-Rack is a CNC machined replacement for the stock plastic rear rack on the Concours 14. You can certainly use the Alu-Rack alone as it was intended, in the event you don't own a Coocase.
Price for both is
$150 $135 $125 shipped to the CONUS. PayPal required for payment.