In my 3670RL, the converter was originally mounted behind the front kitchen wall on the main floor extension, next to the steps. That puts it directly under the anti-siphon valve for the toilet which is known to fail (like mine did). Fortunately, I had relocated both the converter and surge suppressor to a safer location prior to the flood.
In this older photo, you may be able to see where it was. Look along the stair frame on the left and you can see part of the gray housing for it. The black box is my surge suppressor I bought and had the dealer install. Unfortunately, they installed it directly behind the breaker panel under the kitchen cabinet. So I moved it to where it is in the photo. The second photo shows how I relocated both to keep them out of any flooding (read about it from other owners).
To remove the panels, there are screws along the outside frame edge and some in the center where the two panels angle. You may also have to remove the pipe chase cover that runs across the cargo door opening to get the panel out. If you want to remove the other panel, you will have to remove some screws inside the UDC. Be prepared to enter what I dub "The Basement of Doom."
I actually cut access panels into both basement wall sections for easier access to the converter fuses and the suppressor and to periodically check for any plumbing leaks.