Just did this a few weeks ago with a Blaupunkt head unit and would recommend the Connects2 adapter.
Initally I tried the Autoleads adapter but the track skip functions didn't work with it, also it didn't support the head unit display dimming fuction. The Connects2 adapter is working 100% and supports dimming too.
I got the Connects2 adapter from Dynamic Sounds, part # CTSFA004.