Tried to start my 1972 RT2 360 with no luck. I checked and had no spark so pulled the flywheel cover off and checked and then cleaned the points. I now had a nice strong spark. The next day before trying to start I checked for spark and I again had no spark. Then I noticed I had left the ignition key in the on position from the previous day.  Could I have damaged the Ignition coil? I checked the points and even cleaned a second time but still no spark. 
Anyone know where I could get an Ignition coil. 
Thanks 

The way these are wired from the factory the coil won't be damaged by leaving the switch on. The engine ignition system is separate from the battery charging system.

If the wiring is original or mostly original there is a strong possibility of a poor electrical connection at a "bullet" connector or ground connection. Another possibility is a short circuit to ground in the ignition coil primary (points side) circuit.

Also, if the sparkplug cap is original there could be an issue there as they typically contain a resistor that can become an open circuit on the coil secondary (spark plug) side.

Original coils are surprisingly reliable.