The Duraspark II is a triggering device for an electronic ignition system. Coupled with either the stock ignition box or an aftermarket control box, it is a tough, readily available, reliable distributor.Ford Motor Company began using electronic ignitions in 1973 and introduced the Duraspark II system in 1976. The biggest change, apart from the control box redesign, was the large distributor cap to handle the increased spark energy. The system consists of a magnetic reluctor and pickup in the distributor, and an ignition module to trigger the coil. Typically, the distributors have both mechanical and vacuum advance mechanisms. The curve is reset by using inexpensive springs and adjustable advance units. They are found on both 200 and 250 engines and are interchangeable.
They are a direct fit on older 200/250 engines built after 1964 with the 5/16" oil pump driveshaft. If you want to get one from the auto parts store, make it easy on the clerk and just ask for a distributor from a '78 or '79 Fairmont.