A little follow up to this question....
I have an 81 PU, CA emissions.   It has an Oxygen sensor located in the header.   

I just saw that the wire from the sensor somehow got ripped out.  I can't tell where the wire should mate into a wiring harness from the sensor.  I've looked all over and haven't seen it.  The shop manual only has a schematic - not an actual physical location.

Can someone tell me where the wire from the Ox Sensor connects to?