The fuel tank shall have a minimum capacity of 30 gallons and be on the right hand side of the chassis rail or between frame rails. Vehicles with wheelchair lifts located forward of the rear wheels may have the fuel tank in the rear between frame rails or on the left side of the frame rails. The tank shall be equipped with adequate baffles. A drain plug of at least 1/4 inch diameter shall be located in the center of the bottom of the tank. If tank sizes other than 30 gallons are supplied, the location of the tank shall remain as set forth in §A of this regulation. The engine supply line shall be taken from the top of the tank. A flexible fuel hose and oil-proof connection shall be provided at the engine end of the fuel feed line. Fill Pipe Cap. The fill pipe cap shall be of such design as to minimize spillage of fuel when the bus turns corners in either direction. If venting of the fuel tank is done other than through the fill pipe cap, the cap shall be of a nonvented type. Fuel Filler Cap Door. There shall be a door hinged at the front and designed to cover the opening over the fuel fill pipe. A fuel filter with a replaceable element shall be installed between the fuel tank and fuel delivery system, readily available for service. If a fuel other than gasoline or diesel is used, the fuel system shall meet all applicable federal standards.