Thanks Jim, that is very helpful. I wish I would have read your page before I spent the $ on a new o2 sensor.
If I wanted to test the o2 while in the car, will pin 14 in the 38 pin connector display the .1v to .8v or would I have to tap into the o2 sensor wire itself?

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Will
94 E420
82 300DT
77 F250 4x4 429 Cobra Jet
69 Thunderbird 429 Thunder Jet
92 Mitsubishi Galant VR-4