DF, I have the six CD changer and I have never seen any easy, front of the deck, way to add additional capacity. And as I recall from when I read the manual on it's operation, I do no not recall any instructions for this type of operation. And when I think about space to put another changer in the truck, you are pretty limited. The passenger front seat has the jack and tire tool under it, the drivers seat goes down quite a ways. The storage areas under the rear seat is limited in size. It might be a difficult add-on.