I've found (google) how to adjust car/pickup headlights by aiming and measureing at a wall. Set headlight 25' from wall, measure from ground to headlight, then measure where light hits the wall. Set the light to hit so many inches below the headlight level for low beam, and so on. Anybody know how to set the headlights on trucks ? Not with a tool, but by aiming and measureing at a wall. Certain distance to the wall, above or below level, for high and low beam. Web sites that have instructions ??