I am most likely going to rewire the engines while they're out of the boat.. I'm currently running the Crane ignition boxes with the built in timing, a Crane coil and a TB IV distributor. Does anyone know how I could wire up a spot for the standard merc timing chip as a backup? That way if a box should ever fail I could switch over. I also notice some places sell the stock harness and some sell a harness with aftermarket ignition. Anyone know what the actual difference is in the harness?