Okay, we're a little crazy to have a Duramax for a daily driver. But if we go off our meds, we might wind up in a Prius. If you want to hear God laugh, tell Him your plans. N7EEL WROD249
That looks like the back side of a small spike deer skull, the front is probably broke off just above the eye sockets. I have a few similar pieces that I've found over the years.