The Crank Position Sensor (CPS) is really easy to find... and is the only device that the '92 uses to know where TDC is...
Crawl underneath the front of you truck and look at the passenger side of the Crank pulley (near the top). You will see the CPS there being held on by 2 bolts. I couldn't find my research notes... but I still think the "notch" on the crank pulley (between the pulley and the engine) it is looking at is 6 btdc. If you move the CPS oposite the rotation of the motor you will in essence(sp?) be advancing the timing since you are telling the computer that 6 btdc is earlier than it really it. On mine I moved it the rotation of the engine to pull back the timing. I didn't notice any difference in power BUT it did help get rid of some pinging issues (its a bandaid, not a fix)... I didn't slot my sensor, I had enough play in the bolt holes to move a little more than 1/8th inch.
On some of the newer motors there is also a cam position sensor.. so I don't know if you can do the same thing...
~Mark