How much of the 4cyl wiring harness can i keep that will work w/ the V8 wiring harness. What i mean is theres a bunch that go thru the firewall on the pass side into the cab and if i can leave it all attached and that it will plug into the new harness and computer it would save a ton of work. Anyone thats done the swap please chime in w/ what old wiring comes out, im hoping just the stuff in the engine bay.