Start with the planner on this one. The B431 is a 35 gallon dual-role shell, and the single decision that defines the installation is not the tank - it is where the fittings go. Ronco molds the B431 as a blank in Tustin, California and installs every fitting per order, spin-welded or thread-mounted at the marks you supply, exactly as the company has fitted tanks since 1974.
So work backward from your plumbing: print the technical drawing below, stand in front of the bay the tank will occupy, and mark the drawing where the fill hose, the supply or pump-out, and the vent genuinely want to enter. The on-page fitting planner turns those marks into fitting sizes and styles. Order the potable set and this is your fresh water tank; order the sanitation set and it is your gray or black holding tank - same molding either way.
It ships at 98 lb bare and carries about 292 lb of water full, so give it a flat, continuous platform. Alternatives at this capacity are in the boat tank category, and the whole range hangs off the Ronco Plastics hub. OneSource Plastics is an authorized Ronco Plastics dealer.
Technical drawing: download the Ronco Plastics B431 dimensional drawing - print it to plan your install and mark exactly where you want fittings located; Ronco installs spin-weld or threaded fittings to your marked spec.
