I looked @ the bottom & it looked like all the coils were all there. I drilled four holes two for CO2 lines and two for the shanks. All I encountered was foam insulation. Perhaps I was lucky, but it seems to me that walls of my fridge were too thin & have too little access to have any active parts in them.I put the taps on the side, rather than the door for convenience, with the CO2 under the drip tray.
Did you encounter anything in the side wall? Did you need to make sure you didn't hit any lines of any sort?
I'm planning to bring my CO2 in through the side wall but haven't begun yet. I was assuming I'd need to work carefully to make sure there's nothing in there that can be harmed.
I wouldn't say the same about the back. I assume that the wires to the light switch, coldness controller, etc. have to go somewhere.