I doubt it's corian. I know some of the units I looked at used LG Hi Macs solid surface. I would take your Greyhawk to any good solid surface shop in your area, they should be able to identify what material was used and get a close match. These products are poured in batches and colors can vary slightly from batch to batch. If their is an area of countertop where you can see the bottom of the sheet, it may have identifying marking on it. Good Luck.
2011 Toyota Tundra double cab