Crow, I mean blackbird:
Across the speaker voice coil is the easiest, but with that particular radio, you cannot change the volume without changing the recording level, due to the volume control being in the RF stages. In later radios, across the volume control (with a capacitor if the volume control is part of the AVC circuit) will give you the chance to change your monitor volume without changing the recorder, and eliminates a slight amount of noise and distortion introduced by the AF output stages.
Lewis