64 valiant - identify this electrical part?

Radio noise suppression condenser (capacitor). Mounts on the coil bracket, wires up to coil POS terminal.

All cars have three or 4 caps / condensers

1.....If you have a breaker point distributor, one in there helps form the spark, and also protects points from burning This cap has nothing to do with radio noise suppression.

2....One on the back of the instrument cluster to suppress the voltage limiter noise

3....One on the coil for radio noise

4....One either in or on the alternator for radio noise made by the alternator

5....One either on or inside the radio case as a final suppression measure for noise radiated from the 12V power lead. This is usually in an "LC" network consisting of one or more caps and one or more inductors, and sometimes resistors, in a combination circuit.