I just used an autoleads 06-119B from SIO Communications. Fits in the back of my Concert II with PhatNoise and Bose with no problems. Think the differences when you say on the time they are made is that the newer Symphony II's have Quadlock and not ISO plugs. Not sure about the Concert.
If you are not sure, post a message on the SIO Comms forum, Terry Wright, the owner is very helpful. Take snap of the pin-out on top of your Concert and he should be able to tell you which one.
Only prob I had with my Parrot BT kit is that it is too loud. If I had known, he would have soldered on a 5K resistor for me - I just have to do it myself now.