I recently bought a '76. I'm trying to fix some driveability problems. But my immediate problem is locating the EGR valve. The diagram in the Haynes manual indicates there is an EGR valve along with my air pump, and thermal reactor. But there is no plumbing coming from the exhaust manifold to the intake manifold, only that involving the air pump and diverter valve. The emissions sticker in the engine compartment indicates this is a 49 states version but shows no EGR in the diagram, only an air pump. Was there an O2 produced like this? Is there a better shop manual than the Haynes? TIA