Maintenance costs are all about ownership of a vehicle. Comes with the territory. I don't get mad about maintenance costs. Thats like getting mad at the weather. Useless.
Transmission is different, so, no, from that perspective, it is not a plug and play. 3.6L didn't come out until 2012, so there are most likely other engine management issues that would need to be addresses as well (wiring harnesses, sensors, etc)