My 240Z shop manual shows the body harness connecting to the instrument panel harness somewhere behind the glove box and running back to the tail lights and other things. Besides the tail lights the body harness has wires for the fuel gage, dome light, rear window defroster, radio speaker and side marker lights. I've not seen an aftermarket wiring harness for the 240Z, so hopefully you can find a used one in decent shape. If the tail lights still have the original 4 pin wire connectors attached it will make the harness replacement simpler. Good Luck