Challenger radio question

[fireguyfire]

Reinstalling a factory AM radio in my 73 challenger, but putting a modern dual speaker from retro sound that fits and looks like the original dash speaker.
The parts supplier suggested I add a 4 ohm inline resister to the poi's it I've lead to the new speaker, which is easy.
The factory wires coming out of the radio that have a plastic connector where it would have joined to the factory dash speaker has a black wire with white stripe, as well as a green wire.
I'm assuming the green wire would be the speaker negative feedback, and the black with white line would be the positive? Will connect the new speaker to this connector but want to make sure the 4 ohm in-line resistor is on the + lead from the radio to the speaker