Richard, I don't know if you could obtain the exact original harness's, but you could make your own if it comes down to it.
You could buy the connectors from Mouser/Digikey I suspect, but for the sockets you preferably need a crimping tool or its a bit tedious.
There is another way, that I have used:-
eBay has header strips and sockets you can cut to length.
You can cut them to length and solder wires to them, heat-shrink the solder joint for mechanical strength, then put a bit of hot melt glue over the area.? I have done this many times, pictures are of my adapter cable to fit a Nextion display to a Raduino for example.
