Has anyone seen this type of timimg tab on their truck b4? Dose anyone know for sure what 0 deg is on this tab, and what is the small post-like feature to the right exactly for? Any help would be greatly appreciated.

SOLVED!!!!!

Turns out the small tube -like protrusion is a spot for a magnetic pick used for timing. the magnetic pick-up sensor fits in the hole and sits just above the damper, it actually would sense a change in the magnetic field caused by the timing mark passing by and would relay this to a meter, this is actually where 0 deg is, directly center of the hole where the sensor would sit. this sensor/meter was most likely a GM tool. Ill set the base timing as even with the center of the tube as possible to get the timing right.