Brown is likely a ground, grey may be illumination if it had the connector for the digital radio.

What radio are you connecting to? I'd probe the grey to the antenna switch connector for continuity,as that is my guess.

Beware of switched 12v sources indicating false grounds... I messed up on an 85, thinking one wire was ground as it showed 12v from the battery, but when the lights switched on, it was effectively a short.

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