MSD 6AL Ignition Control Box. The MSD 6AL box has built in rev limiter and is compatible with 4, 6 and 8 cylinder engines with 12 volt negative ground electrical systems. It delivers 530 volts to the coil with up to 135MJ of spark energy per firing. Rev limiter can be set in 100 RPM increments with two rotary dials and has built-in LED light for system checks. Box includes wiring harness, vibration mounts and all necessary installation components.