Stephen,
I had a similar noise coming form my speedo area.  At first I thought
that it was the cable but I was wrong.  When I disconnected it from the
speedometer unit it was silent.  I found that the speedo gauge was making
the noise.  Not having the money to buy a new unit I went to work on
pulling the old one apart to fix it.  I found the noise went away when I
sprayed a little WD40 on the magnet that is rotated by the cable in the
gauge unit.  As you look at the back of the gauge you'll see where the
speedometer connects.  A little off-center from that you'll see another
area were you might be able to spray some lube through.  I say "might"
because I pulled the whole speedometer out of the console and then went
to work on it.  You may have to do this also.  The only negative affect
this had was now the needle on the gauge shakes a little bit at lower
speeds.  Other than that it makes no noise and I who knows how much money
I saved.  I'll pray for you on your adventure.

Blake Heinlein   http://www.ecst.csuchico.edu/~bhein/
'83.5 Westy  "Toaster"
California State University, Chico
Mechanical Engineering Student