Hey all,
Today I discovered why I wasn't getting any heat to the back of the bus
this winter ('78).  The cable that operates the flaps was broken:

Under the bus there is a small box that the main heater hose connects
to, which then splits off three ways, to the back vent, the middle vent,
and the front vents.  I removed the hoses from this box and noticed that
when the heater lever was all the way up (all vents open) the flaps in
the box did not open.  So, looked up under the dash, and sure enough,
right where it's supposed to contact the red lever, that cable is
broken.  The one that switches between the heat and defrost for the
front still works, tho.  

Well, I'm not in a mood to run a new cable yet, so I got a coat hanger
and wired the flaps permanently open so that as long as the heat is on,
the heat goes to the back of the bus as well as the front.
Unfortunately, this cuts down on my defroster airflow, especially at
idle, even with the aux. fan running.  

What is involved in replacing this cable?  The cable goes to the top of
the box under the bus, so I can't see what's going on up there.  It's a
really crappy location.  So how much would it cost for the cable and
then how much trouble is it to put in?  Looks like a major pain.  Anyone
done this?

Thanks in advance,
Sean