RE: Battery dead overnight
I dealt with identical symptoms in my '85 except it was intermittent!  I
took to disconnecting the battery when I parked for more than an hour or so.
VOM said I was drawing nearly 1 amp when shut down.  It turned out to be
something under the dash, near the heater controls.  Found this out when I
realized it would come and go depending on whether I had adjusted the heat
level.  Never got a chance to track it down, the van was totaled in a
rollover about the time I figured out where the problem was.  I know this is
a very obscure possible source of the problem, but happened to me.