I wired my rear door subwoofers up to an aftermarket stereo in my late 95 Disco ESGot one of these plugs of E Bay (£16) to make the rear subs work!
Which was wrong
Its this plug with just 1 red & 1 black wire coming out of it.

That fits in here.

Like this.

I had to remove the plug from the e bay lead and connect the wires to the plug on the cars loom also connect the RCA plug to one of the stereo preouts.

A bit of insulting tape and voilà job done :dance:
Unit replaced

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I think this lead from e bay

Is for this later type stereo

But don't quote me on it :lol: