I thought before that it might just be the sound of spark knock. But lately when I give my truck some gas, it makes this weird rattle/grinding noise. I drove to the shop today and when I had gotten here it was way worse. I could put it in gear, hold the brake, and it would rattle like crazy from the front. Could this be a broken flexplate? Or what other possibilities am I looking at? Will check it out further today after work.