Wiring for new modern radio - 260Z
If you are doing a restoration and find that the radio is 50 years old and falling to bits, then you probably will be wanting to replace it with something modern.
There is existing wiring for the LHS rear speaker only and semi automatic antenna already installed by the factory. If you are wanting to use the existing wiring and then just add the extra twisted pair for the rear RHS speaker then the attached file should help you get it done.
The newer radio models have a digital memory whereas the original only had a push button memory of selected stations. Hence the need for a direct battery connection to keep the thing alive but asleep.
This schematic works for the 1975 and 1976 models at least.