Wow, Thanks everyone. Lots of great ideas. If there is a filter it's not visible which means dropping the tank. Of course the tank is hidden by some kind of sheeting on the bottom of the frame rails and runs the full width between them, which also has the rear jacks assembly and and the spare tire rack mounted over it attached to those frame rails. Thanks again. If anybody has any other ideas please speak up. I have reservations at a shop for next Friday and I can already hear my bank account crying.