Pioneer happened to change (not likely) the design of their head unit connector, you'll get one of those Meta cable adapters, splice it to the new connector's wires and plug the Meta cable into the factory harness. That's probably how your old unit was done too. If that's the case, the old adapter can be re-used.
Just pull the old unit and eyeball it - fairly easy to figure out what was done behind the dash. Not like there's a lot of work in doing this on the Z.
