i have one of those acton digital meters and in order for it to work on my 72 340 duster with msd ignition i have to hook the positive lead to the tach output on the 6al box.
A 6AL is a different breed of cat. They are capacitive discharge. An HEI works "more similar" (LOL) to breaker points or Mopar ECU........it switches the coil NEG to ground
