Lay one of the planks flat, and position the ramp end bracket over its end. The sides of the bracket should be flush with the sides of the plank, and the bend in the bracket should slant upwards at the end of the plank. Screw the bracket to the plank using the hardware provided. Repeat this step with the last bracket, and the last plank.
Lay the two planks parallel with their outside edges 40 inches apart. The brackets should be at the same end and aligned.
Position your plywood over the planks so the edges are flush with the sides and the ends of the planks. Screw through the plywood and into the planks using your 2 1/2-inch screws. Use eight screws for each side, so eight screws enter each plank, five inches from the edge of the plywood. Space the screws 12 inches apart.
Set the ramp end brackets on the tailgate of a truck or trailer. Bring the snowmobile up to the ramp and push it up into the truck or trailer. Do not allow the ski's to fall off the edge of the ramp.