I removed the fuse block from the firewall and checked the back for corrosion, rust, loose connection, etc. Everything looks great. I started digging in the dash and found some melted wires that must be fairly old as the copper has turned green...so I may be working with a work around. :/
One of the wires is hot with the ignition on but I separated it from the rest right now.
I probed the brake light switch and got 147 mV and nothing when the pedal is depressed. Thanks for the guidance, I greatly appreciate it.

 

I keep wondering why you are not getting full voltage to certain places and it brings up a starting point.
Usually, power is taken from the starter relay positive terminal on the pass side fender well.
This power goes thru "Fusible Links" on to several places. There are a few fusible links there , some are for ign, lights and other electrical accessories.
They are different colors and just look like a piece of wire, but are smaller gauge wire to separate if a short path to ground takes place , the idea is to carry a heavier load than a fuse , but open if too much load thereby preventing a wire fire. You can sometimes check them by pulling slightly on them and if you feel it stretch it is most likely open and defective.If you are aware of this, it is a good review.
You have found something and now may need to trace the origin and destination of the bare/corroded wire(s).
Did your fuse panel have the signal light flasher on the front of the fuse panel and the 4 way hazard flasher on the backside of the fuse panel?

The flashers , I'm pretty sure are different , one may have 2 prongs an one might have 3 prongs.

 

My flasher relay was buried up in the dash behind the headlight switch. I only saw one up there so I'm assuming it only has one.
What circuit is the brake lights on? Does anyone know if Haynes has the schematic for the brake light circuit? If I'm getting partial voltage at the brake switch, could I wire a new hot wire in as a work around to test?
I've seen several fusible links to check after the rain. Thanks!

 

Sure , you could use a temporary hot wire to power the stop light sw,,,,,,,,,,,,,but you have to be very careful, first where you take the power from for the hot wire and if you accidentally touch any ground, you will blow the fuse for the location where you obtained the power.
The smart way to do that is to place a 15 amp fuse in the line you are using to make the temporary supply. . That way if the unforgiving happens , all you need to do is replace the fuse in your temporary supply.
At least you have 2 choices here.

Most folks don't have a jumper wire with alligator clips on the ends to use, but if you can make one and connect it to the one wire at the sw that shows some power and bring the other end down where you can more comfortably make the temporary connection. Does make life a little easier.