Sounds different to what I have - a single 13-pin connector (all female) as shown here:
IIRC the suggested Autoleads adapter for GTA is also female - i.e. expecting the car's harness to have male connections, which is why I ended up with something for a Jeep!
Note that this does not include the earth/-ve connection. This is connected to the original clock and presumably is resolved via the connections from the original Phillips radio to the clock/display. However there is a spade connector for the earth on the back of the clock that I connected my Autoleads earth to:
Sounds like this is different to what you have, Rupert. However, I found the following in my wiring diagrams book:
3-pin connector:
Pin; Colour (in french, sorry); description
Pin 3; VIO/JA; REAR RH Speaker -ve
Pin 1; JA; Accessories, Radio
7-pin connector:
Pin 1; VIO/VE; REAR RH +ve speaker
Pin 2; VIO; FRONT RH -ve speaker
Pin 3; VIO/RG; FRONT RH +ve speaker
Pin 4; BA/JA; REAR LH -ve speaker
Pin 5; BA/VE; REAR LH +ve speaker
Pin 6; BA; FRONT LH -ve speaker
Pin 7; BA/RG; FRONT LH +ve speaker
Then there is a single connection (M13) that is black (NO) for the EARTH (GROUND) RADIO
Colours:
BA = white
BE = blue
JA = Yellow
RG = Red
VE = Green
VI = Mauve (presumably, this is VIO in the above - I remember seeing lots of purply coloured wires!)
Hope this helps
Jon