The last person I talked to that had replaced a new cat with a 6nz did not have to switch or adapt harnesses, while the engine side may be different the truck side was the same I believe, I will talk to a guy that just put a C16 in a 2012 and see what he say. Also you might want to get the model number right, it's 389.
PDI has come leaping by PP in the recent past, PP box is obsolete these days and is hard on engines, with the availability of the ECM tuning it makes it a no brainer to go with PDI, they are building reliable HP. I mean PP still sells a holse reverse ratation turbo as an upgrade for a cat, when there are cheaper and better alternative on the market that work.