I installed a 2" receiver hitch, lighting harness, and OEM tranny cooler this weekend on my '06 Tribeca.
The hitch went on easy enough, but was a bit cumbersome on my back by myself. It went in fine, though. The toughest part was getting the bolts routed in the right locations as the instructions misled me. After feeling around I found the correct access holes. Once all 4 bolts are in and ready, it's just a matter of holding it up and getting the bolts started. Don't mess around guessing how tight the nuts are torqued on; get a $20 torque wrench and some 1/2"-drive sockets and get it done right the first time. It is recommended that re-torque all 4 nuts after your first tow, also. I didn't modify it as Blackmax had done, and it does hang down below the rear shroud. I like his install better, but this will work fine for now.
Pulling out the jack tray was very easy to access the OEM harness plug, but I had to cut a hole in the tray to get the plug and wires inside. As far as the "clips" that you need to pull out, there are 4 of them, and you can use a philips screwdriver to get the center plug started, and then they pull out very easily. Once they are out, the tray comes right out. I zip-tied the wire to existing cables in a couple of spots, and on each side of the converter box after attaching it so it shouldn't come loose. The harness sits in the jack tray, and for now I'll simply drop the wire under the hatch when needed.
The OEM tranny cooler was pretty simple, too. The instructions are very detailed, and all of the parts are included. The toughest part is checking your transmission fluid level after the install, as it is under the cosmetic engine shroud and way down there on the driver's side. You are supposed to get it to operating temp (drive it a few miles) and then check it at the "Hot" range. The odd thing was, I initially checked it cold, and it was beyond the "Hot" range. After installing it and warming it up, it was still above the "Hot" range even though it should have dropped as there was more space to occupy with the cooler in place. I'll check it again after using it some more. If it is low, I am assuming I'll fill it by running a tube down to the dipstick neck and running fluid down that.