Sorry for any ruffled feathers. One expects to find Car Enthusiasts at sites like this, especially those enthusiastic enough to do a little basic research.
The Part Number you are looking for is GM P/N 95975191. I got it by going to gmpartsdirect.com, and clicking on the Catalog link, and drilling down from there. I recommend you verify the part number before ordering.
In the diagram, it is Part #8, which is in place of Part #9 (Which you have). In fact, anybody who opted for an inflation kit versus the spare, will have this same floor panel. Item #10 in the drawing will also come in handy, but there is not a price in their system yet. As an aside, is item #11, from the drawing, not included in the ECO?