I found this and thought it would useful Obs to Lsx wiring made simple Ok so if any of you guys have been keeping up with my build its been a long road. But i have found the easiest way to run the wiring for the ls engine into a 96+ Truck. This will only work in those trucks. what i have found is that you can remove the pins from your factory harness and install them right into the ls harness and pcm. that way you will be using the OBS fuel pump relay, VSS signal, Check Engine light, and brake signal. basically if you decide to do your own harness or have one made you will remove from the green connector completely 9 - Fuel Pump 46-Check Engine 16-4wd low (4wd only) blue connector 33- brake signal then from your stock obs harness you will remove the following pins and insert them directly into the ls harness Black connector plug 1 fuel pump 5 Check engine 10 Brake signal 23 4wd low (4wd only) this saves you from having to cust and splice wires and makes for a seamless integration. as far as the starter you can reuse the factory PNS switch and obs solenoid wire which should be purple. the other connections from the harness like ignition and constant power should be pretty straight forward.