Factory tach wiring

There was a thread in the past about the differences in 67 and 68 B'cuda bulkhead connections, wire positions. 68 got hood mounted signals so wires were moved about for that and reverse lamp wires too. I don't doubt that they could have had a wire harness for a 4 speed or formula S car and that harness had the tach wire in it. Who has seen it all? Not me.