[submariner409]

EGR valves are usually bolted to the exhaust passage crossover in the intake manifold and dump into the intake area directly under the carb. The metal box sounds like some sort of air door for controlling heated inlet air. Not sure, but FYI, EGR controls NO (oxides of nitrogen) while CO (carbon monoxide) is from incomplete combustion or a slightly rich mixture. Not sure if your car had a cat yet, but a cat also lowers CO.