So my truck has been running fine for the past 1000k since I rebuild the heads and yesterday I was pulling out of a ditch and hit one of the supports for the frame on some concrete but I checked and it just scraped it no serious damage at all I thought at first it hit the rear axle but there is no obvious damage at all. So I drove home around thirty miles or so and stopped at the bank, left the truck running and I came back out and drove it away and it started lunging violently in gear if you give it more than about 10% throttle. It seriously feels like when your pulling a trailer and the trailer yanks on the back of the truck. Weird thing is, the rpms and the speed do not change at all when it lunges??? Any ideas gentleman? 94 mm v6 5 speed. O and when I got home I checked the oil in the diff and it has plenty no issues.