This pin out is looking at the plugs on the car harness

if you want a ISO adaptor the number you are looking for is PC2174 usually about Ł7 or Ł8

MK1a connections

The colours in brackets are variations that I have come across
light blue(blue/brown) = permanent +12v
pink/blue = ignition controlled +12v
green = +12v from the dash lights, when on
white/black = Earth ( ground )
green = subwoofer remote turn on
white = left speaker -ve
yellow (yellow/black) = left speaker +ve
black/red = right speaker -ve
red (red/black) = right speaker +ve