I do have an amp meter, so I just tested it and I have a 1.0 mA draw. Is this significant?
So this is stupid but I forgot I reattached the battery, accidentally touched the metal horn button cap to the center rod and just got a full 12V up the arm. There has to be a major short right? There should be power running through the center steering axle?
If I have 0.001A of draw then this is nothing
If I measured 0.01A current draw then I would think the draw is from a clock/memory circuit of an aftermarket radio or an aftermarket engine control module.
On my 68 Chevy II Nova, at most I've gotten 0.01A draw and this is due to the aftermarket Pioneer radio under the seat. With it not connected I get 0.00A draw.
When I've measured other cars, if I have 0.03 or higher, then this requires the car to be started and driven for a few miles to bring the voltage back up or be put on a battery tender if it is to be sitting for weeks at a time.
Try this, charge up the battery with it not connected to the car and then after taking the charger off, maybe about 4 hours later take a voltage reading and it should be around 12.5 or so. Now come back a day or two later and see if it's the same. If it's dropped to 11V or so, then the battery is toast.
How did you figure out it was a full 12V up your arm ?.
Do you get the same shock if you go under the hood and touch the battery positive terminal ?.
Maybe too, do an amperage draw test between the horn wire and a ground and see what you read. If you are getting shocked by a potential of 12V at the horn wire and your body, one should be able to get a meter reading of this.
A major short should blow fusible links unless there are none on the car between the battery and the short. If there are no fusible links then a dead short should be melting some insulation off of some wiring.