1.5 FUEL SYSTEMS
Location: All fuel tanks, lines, pumps, valves etc., must be outside of the driver's compartment and within the confines of the frame and/or steel body. Cool cans, in full-bodied cars, must be mounted a minimum of 6-inches (15.2 cm) forward of firewall. Fuel blocks must be located at least 6-inches (15.2 cm) forward of the flywheel/bellhousing area.
Tanks: When permitted by class regulations, fuel tanks located outside body and/or frame must be enclosed in a steel tube frame constructed of minimum 1 1/4-inch O.D. x .065-inch (31.8 x 1.65 mm) chrome moly or .118-inch (3.0 mm) mild steel tubing. -->> All fuel tanks must be isolated from the driver's compartment by a firewall completely sealed to prevent any fuel from entering the driver's compartment. <<--All fuel tanks must have a pressure cap and be vented outside of body. A positive-locking screw-on fuel tank cap is mandatory on all open-bodied cars. Insulated fuel tanks prohibited. When used, fuel cells must have a metal box protecting the part of the cell which is outside of body lines or trunk floor, excluding hose connection area in rear. All non-metallic fuel cells must be grounded to chassis.
7.5 FIREWALLS
Each car in competition must be equipped with a minimum .032-inch (.8 mm) aluminum or .024-inch (.6 mm) steel firewall, extending from side to side of the body and from the top of the engine compartment's upper seal (hood, cowl, or deck) to the bottom of the floor and/or bellypan. Firewall must provide a bulkhead between the engine and/or fuel tank and driver compartment. In certain instances fiberglass, carbon fiber or other composites may be used. See Class requirements or consult FIA. Use of magnesium prohibited.
Yep, the back seat does not cut it as a firewall, still need one.
Full NHRA Rules
http://www.qsl.net/wd4ngb/nhrarules.htm