I had Highway products build me a toolbox that fit under the roll top cover so I could use all the space available. I'm sure there are tank companies out there that can do the same thing. http://www.800toolbox.com/
2001 3500 GMC D/A CC Summit White<br />J&J Stainless Tubless Tapered Boards, J&J Stainless Mud Flaps, Pace Edwards Roll Top Cover, Power Tailgate Lock, Smitty Built Sport Bar,Piaa Off Road Lights, Lund Painted Deflector, Weather Tech Visors, Highway Products Custom Made Toolbox, Perma Tech Tan Liner, Cobra CB, K-40 Antenna, Prodigy Brake Contoller, Valentine 1 Radar Detector, JAE Wheel Sims<br />Chrome Exhaust Tip, Futomo Drain Valve, X-Mount Mirrors, Velvet Ride Shackles, Pullrite 5th wheel hitch 20,500, Street Pilot 3, VDO Boost and EGR Gauges, John Kennedy 4\' Exhaust, The Juice, Transfer Flow 56 gallon tank and fast fill neck, Bilstein Shocks.<br />Pulling a 35\' Excel Fifth Wheel<br />Pictures at <a href=\"http://www.picturetrail.com/curlyq1\" target=\"_blank\">www.picturetrail.com/curlyq1</a>