Another thing you might want to look at is whether you have the right arms and blades on the truck. A lot of times the arms and blades where switched to a more modern setup. The original vacuum arms and blades are very light and not a lot of spring pressure. The blades are connected to a single kinda swivel joint in the middle and flop back and forth. Look in a vender catalog for the correct year and you may find a different type of arm and blade then you have on your truck.
