svard75 wrote:Also Aluminum to steel causes galvanic corrosion should we perhaps have a pad between?
They have to be electrically conducting from one of the metals to the other for that to happen. While our cars do use the body as a ground path back to the battery, that area down there is not really a place that would ever be the quickest path back, so electricity wont be flowing from one area of the body (steel) through the plate (aluminum) and then back into the body just to get back to the battery.