Can someone tell me what is missing here???

An EGR vacuum control switch (3656 660 before March 15 1973, 3780 140 after March 15 1973) or a blockoff plate 3656 649 depending on the vehicle's original emission control configuration. Most of them I've seen, including my '73, have the blockoff plate. The widget next to it is an OSAC valve. Bypass it -- run the distributor vacuum advance hose directly to the correct port on the carburetor -- and you'll have better driveability, performance, and fuel economy with no downsides.