Wiring Speaker Volvo 940

Hello, I don’t drive a Volvo but help a colleague install a new radio. The old developed radio is not an original Volvo radio. During the expansion I noticed that the whole radio electric was bent and botched, so – here a lustre clamp, – there a power thief, – another extension cable, – another additional fuse, – additional crossover etc. There is under the cigarette lighter compartment a white multipole plug, on which apparently all necessary radio contacts (mass, +30, +15, light, antenna… ) incl. speakers connected to the factory. On this plug I could control the front speakers in the door. For the power supply (+30 +15 mass), antenna signal, light I have built my own wire harness of old wires (so a little longer, shrink hose on the soldering points etc. ). This also works great Now my questions about the speakers. 1. On the console there are also speakers to the right and left. Where ends the Cable of these loudspeakers? Does anyone happen to know the cable colours of these wires? 2. Where were the low-tone tweeters installed in the original factory? (in the door, in the amature board or in the radio shaft)? 3. Were the loudspeakers connected in the back door on the factory side or are there any features that the speakers lack in the back door? Background: I can’t find any cables in the radio shaft which are intended for the rear speakers. can anyone help me with my questions? Yours sincerely Hein_nieH