the 69 harness is one piece. I rewired a 69 Fastback with a new harness.
The wires for the zener diode may be different because the Fastback had the diode mounted in front
of the left side panel and not on the right hand side Z-plate as Roadsters or S-Types.
But I mounted an electronic rectifier anyway.
Later harnesses from 71 on had a separate front piece for headlamp wiring.
As DogT mentioned, there is only the extra wiring to the Triconsul switch.
On my 70 S-Type I used the later two piece harness which was a lot of extra work to make it fit .
I chose it because of the wires for the indicators which a mandatory in Germany.