It's possible that the model name for the Hawken was mislabeled by the eBay seller.
Pecatonica River sells 98% inletted drop-in stocks for the TC Hawken and Renegade in 7 different grades of wood including walnut & cherry.
http://www.longrifles-pr.com/thompsoncenter.shtml
American black walnut is the type of wood that Marlin uses to make some of their stocks from, and some custom stocks and handgun grips are made from it too.
It's a good wood.