Almost plug-and-play. The plastic "cage" or frame is suited only for the digital clock/temp gauge, and not the complete OBC. You can either dremel / cut / file out the back of the cage so that the complete OBC can snap in nicely, or pull the whole cage out and replace it with one that accommodates the complete OBC (can be had from a breaker or ebay). Other than that, it's pretty painless, I did the swap myself some time back.