S Class 6.3L With Bosch 231119004 Distributor / With Bosch 231128003 Distributor 1971, Ignitor II Adaptive Dwell Ignition Control (91884) by PerTronix. The has many of the same great features that the Ignitor has, but its smarter. units sense the coil current level and use a powerful micro controller to adjust the dwell. Variable dwell helps to maintain peak energy throughout the entire RPM range. systems develop up to 4 times more energy between 3000 and 5000 RPM than standard ignition systems. High RPM performance is improved when used with the Flame-Thrower II super low resistance (0.6 ohms) 45,000 volt coils. If you appreciate value, nothing else comes close to this superb PerTronix product. Backed by a high level of performance, it leaves behind all its competitors.