How ever fast you can get going by just putting the truck in gear (without touch the gas) in less than 50 ft, is how fast I was going.

Why I'm so mad is that I could have prevented the dent if I had got out to look when it hit.. The shelf hit, I looked in the rearview, saw the shelf was lifted a little, and put it in reverse not realizing the shelf was under the carport. Even though I barely moved back, the tension of it being caught on the carport, and the way I had it strapped down, caused it to flip forward with force.

I guess I'm better carpenter than mechanic as there is NO damage to the shelf unit, which I had built.