Autoleads do a converter that allows you to use Sony or JVC (and maybe one or two other makes) with the built in controls. I have one fitted on my Marea that allows me to use my Sony HU.
Do a search on here and also FiatForum as I made some posts about it when I sorted it last year.
I have a standerd marea head unit with CD function and the steering wheel complete with all components to make the steering controls work.
But i take it your just after a head unit??
Scotty