Doing some ebay searching and I came across this. It says hitch mount, but for the life of me I cant figure out how it attaches, any one have any idea?
From GMPartsDirect:
Used with P/N 12495707 to remount license plate to remain viThe lighted License Plate holder is used when your regular holder is block from view. This is the required License Plate holder for the Hitch mount bicycle carrier and the hitch mount ski carrier.