trouble with connecting aftermarket radio to '79 pontiac GP

I'm having trouble building my aftermarket radio into a 1997 Pontiac grand prix.'i took of the original radio and now i cant find the power
and zero cable anymore. i was wondering if anyone out there could tell me what the colours of these cables should be? i found a pink and grey coloured cable that might just be the cables , but if i connect mu multymeter to them i get nothing at all.
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