I have a 15 xlt fx4 screw with 3.5 eco. In the front under the motor before the skid plate it's uncovered and I can see salt and grime getting onto the motor components. Is there a cover I can order? Seems strange that there is an open area there letting the grime in . also the 36 gal tank is covered by plastic skid plate. Should it be metal for the fx4 ? The rest of the truck seems fine .