Reverse lights, from start to finish
Ok, so my Eski gets ever closer to registration.
I decided to tackle the reverse lights, which have not worked since I bought the car a year ago. I was told at the time that the reverse light wire got pinched during the installation of the Type 9, I now have more information (based on my visual inspection) that the reverse light switch was fairly well smashed during the installation of the gearbox.

Unfortunately, the plug to the reverse gear switch seems to be gone as well. I have one solitary lead inside the cabin at the gear selector hole which seems to be an earth? I would have thought it would source the earth thru the gearbox.
The type 9 reverse switch looks like this on ebay, which I am about to order:

My questions are:
Does the reverse switch earth through the gearbox? If so, what are the two contacts for?
Does the wire from the reverse light switch go through the gear selector hole into the cabin, or along the underside of the car and in through the firewall?
If I can't find any wire/plug for the reverse switch (which seems likely so far I have looked all over the area), does anyone know where I can buy the plug to suit the switch, new or used? I can wire it in myself.
Any help is greatly appreciated.