Assuming you have an external amp fitted in the usual place up amongst the wiring behind the dash on a strength strut above you right knee you will have to by pass that as all the speakers wires come from that to the various speakers
What you wanted was an Autoleads PC2-19-4 Car Stereo Harmess with amplifier baypass lead for 740/760/940/960/850 etc. You will find them on eBay etc and, can view details on Autoleads website. It comes with all compatible plugs/sockets to connect to the existing loom plugs/sockets.
Bob.
