My dad told me of his anti theft device he used on his 1939 Packard convertible that he had when he was in high school. He setup 4 Model T coils, positive to the battery and the negative he ground to the chassis, you could use an Accel Super Coil, about 24,000 volts, today. He also had a toggle switch for on/off hidden under the left fender. He said his car was never stolen or broken into, although he did find burnt skin several times on his door handles and there was the occasional loud meow from the local cats that would try to jump up on the car for the warmth. Although, this might be illegal nowadays

Dan Snyder #5537