Disconnect the battery and pull one or 2 of the unworking bulbs.  Then
use an ohmmeter to check from the negative of the socket to the
battery negative.  Make sure the battery disconnect doesn't kill the
ground.  If there is good continuity, start workiing backwards from
that point.

This may not find it but is an ok first step.

Unk

Headlight swtich or associated circuit breaker.

I used a volt meter and found that I'm not getting power at any of the
4 fuses at the top row of the fuse box (stop/hazard, tail, horn, and
air horn).  On the opposite side of the fuse box (firewall side) there
are a few buss bars and a lot of wire-to-post connections.  Most of the
connections are corroded and rusty, but I was able to get a voltage
reading from them all.  I cleaned about half of them but stopped after
I broke the post on one while trying to get the nut off.  I was able to
fix it, but what a pain.  I decided I better seek further advice before
I risk damaging more. Are those firewall connections possibly my
problem or should I do something different first?

I'm assuming that since I don't have power at the fuses that it rules
out such things as the headlight switch and dimmer switch.  Could it be
a bad relay?

I don't see that the lighting harness connects anywhere on the firewall
side of the fuse box.  I tried to to trace it into the passenger
compartment, but don't see that it ties into the fuse box in any way.
As a general knowledge question, where do the fused circuits exit the
fusebox?  In the firewall area, or inside the passenger compartment (or
both)? There are a lot of wires connected to the passenger compartment
side of the fuse box that hook up to the front of it too.  But, they
all seem secure.

The lighting grounds I checked show no resistance, as well as any other
chassis grounds I could find.  Could it be a ground problem if I'm not
getting power at the fuse?

Is there a temporary way to bypass the problem (or at least get brake
lights).  I'd love to honor my reservations this weekend at the State
Park at Deception Pass!   Thank you.  Erik

I think I found the problem, but as usual, there are a couple more
speed bumps I have to get over.  I found that the fusible link wire
that attaches to the solenoid on the starter has basically
disintegrated.  Two 10 gauge wires that are molded together attach to
the 8 gauge fusible link wire.

All I could find at the auto parts store (5 minutes before they
closed)  was a "HELP" brand GM 14 gauge fusible link wire.  The package
states that it is to be used with wire 2 sizes smaller.

I'm sure the fusible link I bought wouldn't do the job because it's a
much smaller diameter wire, but I was thinking about putting one of
these fusible links on EACH of the 10 gauge wires, so I would have each
wire protected separately.   Do you think this would provide the proper
protection.  The Chevy dealer parts department isn't open on the
weekends, so I was hoping to find an "off the shelf" solution.  As
another alternative, can I use an in-line fuse holder?  How big of a
fuse?  Special type of fuse?  Does that offer the same protection as
the fusible link?  Or, should I just wait until I can get the proper
parts?

Thanks for your help! Hopefully, I can get out of town after all.  All
of the planets at the job lined up perfectly, allowing me to take a 5
day weekend!

Erik