So I am trying to figure out how to convert a harness of my wrecked 88 764t to fit into my 87 744t which badly badly needs it. So far I can really only see two problems and one of them should be easily overcome. The drivers side end of the harness needs to be extended about 10 inches which I can easily take care of, but would like some suggestions as to what type of wire I should use(it isnt in a very high heat or oil exposed area so im not too concerned). The second problem is this: On the 88 the wires from the ignition coil go into their own seperate shrinkwrapped harness(along with the RPM sensor wire I beleive) which goes along the top of the engine bay and then into the firewall connector on the drivers side(single 8-pin). On the 87 harness there is an 8 pin connector on the passenger side that goes into a shinkwrapped section and the wires from the coil also go into the same section but not through the 8pin connector. From here it appears all the above mentioned wires go around the back of the engine and to their various connectors(starter TPS injectors Temp etc etc. On the drivers side end of the harness I have 3 connectors(the 8-pin grey, the white ground, and then this other connector that is a 2 pin grey) I am wondering what wires this third connector(the 2 pin grey) is going to. I should note that on the 87 the RPM sensor is not in shrinkwrap with anything else, it just goes across the top of the engine compartment and then into the firewall(harness). I know all of this is probably a bit hard to visualize without it being in front of you but Ill see if some volvo electrical genius is lurking the board.

I also know there are a few ways I could remedy this on my own however they are all non-options for me for various reasons:
Order a new harness? Dont have the $
Look at the wiring diagram in my Haynes manual? I dont trust it and can only understand some of it
Cut open the 87 harness and trace wire colors? I would but this car has to be driveable on saturday so I dont want to screw anything up too badly.

Thanks in advance and if I need to atttempt to clear anything up please let me know
John Parker
PS if anyone has scans of the volvo factory wiring manual that would help IMMENSELY!