It does sound like your #10 (Black with yellow tracer) is going directly to ground. Perhaps remove the parking lamp bulbs (1157, if I remember correctly), and side marker bulbs, and then check the BLK / YELLOW wire to see if it is grounded somewhere (unplugged from the firewall). With the bulbs...
I agree with @pschlosser. I'm positive you have a short to ground somewhere else. Wiring, wrong bulb somewhere. Unplug the lighter and try again.
Is this a new issue with the car? If so, go back to the last thing that was 'messed with'.
You can test the switch with an ohm meter. The running...
The number does not show up in any of my parts books. I do not have the Dodge truck books from the 60s, so it COULD be a truck switch of some type that someone used in place of their top switch?
Pair of restored dimmer switch and wiper switch knobs. Both have the internal clips present.
Restored by my wife, as I'm too busy rebuilding E Body (and all MoPar) switches.
My wife has been selling these on ePAY but I'd rather save the $$ (for all of us) and sell directly.
$55 pair, delivered...
You have it mounted correctly. If you look real close you will see "TOP" lightly stamped into the red back, above the terminals.
I have 3 rebuilt ones, all have "TOP" stamped.
The thing hanging off the side is the resistor set that regulates the speed. It is in fact a 1972-1974 3sp switch. It will work fine with your motor (assuming you have a 3sp / variable speed motor.
If M&H doesn't come through with the colors let me know.
Devin