1993 Chevrolet S-10

Engine Performance problem
1993 Chevy S-10 6 cyl Two Wheel Drive Automatic 115000 miles

I have a 93 S10 P/up 2wd 4.3 tbi z engine. The code I'm getting is for the knock sensor/ esc problem. This engine had the heads replaced before I got the truck, and I'm not sure of the knock sensor location or if it is correct. There's one on the back of the pass side head that has a 1/4 inch stud on it, ( smaller than the one from the parts store), the one one the driver side is in the water jacket on the side of the head between the back two cyls, and it has a stud larger than the one from the parts store.
Which one is the real Knock Sensor, and what is the correct part? The base timing has been set correctly, but it still throws code 43 and runs rich and rough, HELP!

By the way a " real" mechanic changed the heads because of an overheating issue. The freeze plugs were rusted out. This $100 truck is adding up.
September 24, 2009.

The KS is on lower left and top rear of engine -The KS control module is on no.7 and the KS is on J-see below

Sep 25, 2009.
My 93 has 2 " knock sensors" as per first question, the picture shows the sensor in a different location than the sensors on my truck, and there is not a box on the firewall that your drawing shows. My 91 s10 has the box on the firewall, but these two trucks have different sensor placement. Is there another drawing that shows 2 knock sensors an no box on the firewall? The wires for the sensors appear to be at the right places and hook up ok, but would both sensors go bad at the same time?

Sep 25, 2009.