the only func dash kit is to relocate the AC as well as Give you the proper size hole for a double din or single din sized radio. The dash kit has no interaction with sync.
As far as these adaptor boxes, your going to have to buy them if you want to keep things like steering wheel control. Each manufacturer has a box for there unit...example... I have a Sony in dash screen. So I bought a Sony to 2012 mustang
interface box, I also needed a Sony to ford antenna adaptor, if I had steering control there is a box for that as well... And so on. There may be a box just for sync even...