These were NOx retrofit kits. Cars from 1966-1970 had changes to meet HC and CO standards (some of the first real smog laws after the PCVs). After testing them again, and finding that they had the opposite unintended effect of raising the NOx emissions, the state of CA decided to "retrofit" these cars to lower the NOx emissions. The retrofit took place when the car was transferred to a new owner or brought in from out of state. There were a number of approved kits, but the cheapest was the most common. That's the one shown. It consisted of 2 vacuum plugs, the decal for the speedometer, and the book. The instructions were to retard the timing and remove the vacuum hose to the advance on the dist. and cap both fittings. Now you know why so many people hated smog stuff back then.