Behind the passenger seat you will find two black cable boxes. Those are zero can boxes painted black. One is on the left of the VSR and one is in between the Flux Capacitor and the gold relay boxes. Below are some pictures from the a-car before restauration

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    The cable boxes each had 4 cable glands screwed in. The closest ones you can easily find now are the Skintop cable glands.
    You will need 1xPG29, 3xPG21 & 4xPG9). You can find the layout below 

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