Yeah, I agree about the sudden shock loads. My brother was driving my dads 83 Ford 1/2 ton. Had the 300 6 and a 4spd with the 9". Spinning in the gravel to pavement. When i caught it took out hte rear and the trans. Split the case down the middle. The 9" had some broken teeth. The 300 isn't known as a horse power machine especially for 83. Anything short of a weekend cruiser thats driven nice, this rear don't have much hope. I killed 3 with a stock 318 and 4spd. Of course I wasn't easy on it.