Hi Gadget , the 3rd relay holder is for cars with aircon , as for the 8 way plug 2 wires are not used ( Brown and Grey )

The brown with a green Line is rev counter there sound be a female spade connector near the end to join that .

The 8way plug
The light green and orange wires are 12v live ( Need to be fused )
Yellow fuel pump output, live to pump
The light blue single wire is water temp

I have a diagram at home but i'm in europe at the moment

Pm me for any more info