wiper motor differences

[Michael Deakin]

About a year ago, i fitted a new wiper harness but unfortunately, it came with the 2 wires for the ballast resistor, which my car doesn't have.
I fitted an engine ballast i had but it still wouldn't work, despite there being power at the motor and the motor working. Then i tried fitting another larger switch from another 69 Dart, which i think, had an extra speed and now the motor turns.
My questions are, what power does the wiper ballast put out, is it 0.5 OHM, the same as the motor one and why do some wiper motors have ballasts and not others.
Mike