Polarity of the wires on the crank trigger sensor will likely affect your timing on a MSD Ignition System. MSD advises that the correct polarity is the one that has the most timing advance on a Digital Ignition. For analog ignitions, this is opposite, and the correct polarity is the one that has the most retard. You must try both polarities to see which one generates the most advanced setting on a digital ignition (or most retard on analog ignition).
Flying Magnet Crank Trigger Sensor #964
3/4-16 UNF Flying Magnet Crank Trigger Sensor. Directly replaces MSD #8276 and features same style electrical plug and thread size. Compatible with MSD Ignition Systems and others that use Flying Magnet Style.
Available on backorder