Give me back the rear mono button of the late 80s

In the very late 80s and early 90s I did a lot of travelling around Aotearoa New Zealand in Avis rental cars, mostly Toyota Corollas and Coronas. They all came equipped with Alpine car audio that had a really good button for rear mono. So you had stereo up front and punchy weight from the rear parcel shelf speakers. In all likelihood, given capitalism was alive then too, there was probably not…