77 Scout wiring harness, then some...

["Matt and Leah Seay" <mrseay@domain.elided>]

    I'm checking out my beast and find that the previous owners did some
interesting things to the wiring harness.  I'm finding a few burnt wires, a
few cut wires and lots of weird connections.  I pulled the wiring diagrams
from Binder Bulletin and started tracing lines.  Didnt quite match
everywhere.  Weird thing is...that it ran like this.  Most of the of the
gages didnt work and sometimes the starter would not disengage if the engine
didnt turnover, but she still ran.
    Does it stand to reason that I would want to replace the wiring harness?
Does anyone have any suggestions as to where to get a replacement? I looked
at Centech wiring, but I didnt see anything for Scouts w/ electronic
ignition.
    Second question, there is a box located under the master cylinder
attached to the firewall that I cannot figure out what it is.  I think it is
some sort of sending unit because the wires leaving it go towards my gages
and there is a cable attached to it from the transmission. The speedometer
cable also attaches to this box. I've looked for it on all the wiring
diagrams I have, but have not been able to figure it out.  Last week, I
looked at some older Scouts at junkyards and none of them had this unit.
Help is greatly appreciated.
    Semper Fi,
                            Matt Seay