OK...my electrical has officially kicked the bucket.
When I start the engine, the: lights, horn, and cab light does not work at all.
If I rev the engine to about 2500 or so, then everything starts working and
will continue to work when I let off the throttle. Another strange thing is goin
on...... my lights turn off when I turn the engine off.... now, ive owned a few
of the older chevys in my short time, and the lights typically do not turn off with the engine, ALSO everything working after i rev the engine should indicate that my system
is charging. It doesn't. any ideas?http://www.dieselplace.com/forum/smileys/Approve.gif

I would look at the ignition wire connection at the battery, follow it back into the cab and figure out where the bad connection is.

I don't think the ignition connection is at the battery, it is at the solenoid, and if there is corrosion or if the connection is loose it will not be reliable. I would check there for problems first.