How you integrate your harness into the 92 harness is really up to you. Personally, I would remove the stock PCM and all wires that run back to the original engine. The original harness has power leads for the PCM, injectors and many other items that come directly from the fuse block in the truck. Be sure you mark each and every wire before removing it so that if you have to come back to something you'll know what it was and where you removed it. Do not remove the speedometer calibration box that is under the glove box, you'll need it later for the ABS to work properly.