where does the wiring for the rear o2 sensor on a 2.2 s10 connect to?

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i have a 95 s10 2.2, 5speed. when i got it the cat had allready been removed. i got the fac tory cat setup from a buddy but the wires for the o2 sensor after the cat are not anywhere to be found. does anyone know the location that wiring goes to, or which harness it connects into? i'd like to find it and hook it all back up. <!-- / message -->
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it should be bolted up to the pass. side of the&nbsp;tranny with a 7mm screw, along with a few other plugs and wut not. should be, depending on the owners of past and what has been done to the truck

cool, thanks, i need to get that check engine light off.