No, my 40k-mile slant-6 car, with factory-everything under the hood (cap and rotor, vacuum hoses, heater hoses, PCV valve, all EGR components) came with the blockoff plate. So have most of the other '73s I've seen over the years in the yards. The FPC is a little vague on which cars got the control switch and which did not -- California vs. 49-state/Canada, maybe? -- but there were a great many '73s with EGR and without that switch.