I'm doing a motor swap in my 1997 gmc Sierra 2 wheel drive I'm in the process of replacing my old 4.3 vortec with a 5.7 vortec I have the ECM for it and everything I need but I can't use the old 5.7 wiring harness due to wires being cut and I was wondering what I needed to do to make the 4.3 wiring harness work?