This pack allows you to build an ignition system tailored to your needs, giving you the freedom to choose the coil and the best spark plugs for your car. It is suitable for vehicles with a negative earth battery, equipped with a 43D4 or 45D4 distributor. These distributors were typically fitted from 1974 to 1980, although many early cars have had their original distributor replaced with the later 45D model The 25D and 45D distributors are quite different and easily distinguishable. Please refer to the photos for comparison. COIL OVERVIEWAll Chrome bumber MGB models were fitted from new with a 3 Ohn non-ballast coil All Rubber bumber MGB models were fitted from new with a Ballast 1.5 Ohm coil ,these models were fitted wuith a ballast wire in the loom and 95% remain . It is possible to bypass the wire and use an earlier non-ballast coil but this is not recomended.