Hot Rods 51 Plymouth Ignition Switch

Rewiring a 51 Plymouth coupe. Customer wants to use original ignition switch. It has 3 terminals plus a wire inclosed in metal. (see photo) Anyone know what the reason for that metal housing is.
This is not my car, I did not take it apart, the original harness is long gone.

 

I could be wrong, but I don't think that's part of the original wiring.

 

yeah, it's original. It was pretty common in the 30s -40s to have an armored ignition wire from the lock to the coil, so no one could hot wire the car.

 

Very Early Anti Theft Device VATS in newer cars

 

So, then that is key on ignition hot?

 

Yes

Ben

 

Back then, the device was called an Electrolock....

 

Thanks all. That helps I am not a mopar guy but, learning.