I did the box myself on an '08.. Does the box come out or is it molded in?
You need to take it out scrape it down, wrap in copper refrig. tubing then reinsulate. I installed the unit in the wall of the aft berth, put a relay system in so I oculd use the same cooling pump as the AC. Sounds simple but it took a while and a lot of sweat. Did it for about 1/2 what I was qouted from an outside vendor.
http://www.seafrost.com/baitfreezer.htm
This company was a great help.... I bought the equip. from them
I have pictures of the process if you want them, I can email.