Dyna III for 1974+ MGThe Dyna III allows the coils to build up to maximum current, and even at high RPMs, you get a more powerful consistent charge to the plugs for top operating efficiency. The sealed aluminum module is unaffected by dirt, moisture, oil or vibration. We designed this ignition for use with stock coils, but it can be used with other coils that provide at least 5 Ohms of primary resistance.