It did already have the cutout, grill, etc from the factory, and I'm sure you could probably get the panels. Sorry, I don't have the part numbers, and I'm currently in an area without access to a garage. It's 14 degree's outside, so honestly, I'm not going to spend the 45 minutes it takes to get them all out to look for the part numbers.
What I can tell you however, is that these are my stock panels in an 03 Limited with the JBL system. I would assume the panels are the same for any of the JBL systems w/ factory sub. You might be able to pull these parts from a U-Pull-It type place way cheaper than the dealer. You may also be able to trade out your panels with someone who's gone the separate box route, on here. There may be people who want the cleaner look of not having a speaker grill on the side (passenger rear) panel if they're not using the stock location.
I can also tell you that I used the factory sub box. In the factory configuration, it servers double purpose of mounting the stock amp and stock 8" sub.