I have never seen a disconnect box that would line up with the holes for a single gang junction box like you have. (doesn't mean they don't make one, I just haven't seen/used one)
If I was in your shoes, I would find a disconnect box with a knockout in the back so that when you placed the box over the junction box, it would be fully covered. The junction boxes I have used in the past either have 4 holes on the inside to fasted to the wall or a couple of tabs on the outside. Your going to have a stud either to the right or left of the junction box. I would try to get at least one screw into the stud and then since it looks like you have stucco, I would drill a hole and use conical anchors for another screw or two
I tried finding a pic of disconnect box to show the hole pattern - and you can see the 4 holes in this one that are pretty typical
Look what else I found
anchors for stucco - they even give you the drill bit
https://www.homedepot.com/p/Klein-Tools-201-Piece-Conical-Anchor-Kit-53729/100662394
If I was in your shoes, I would find a disconnect box with a knockout in the back so that when you placed the box over the junction box, it would be fully covered. The junction boxes I have used in the past either have 4 holes on the inside to fasted to the wall or a couple of tabs on the outside. Your going to have a stud either to the right or left of the junction box. I would try to get at least one screw into the stud and then since it looks like you have stucco, I would drill a hole and use conical anchors for another screw or two
I tried finding a pic of disconnect box to show the hole pattern - and you can see the 4 holes in this one that are pretty typical
Look what else I found
anchors for stucco - they even give you the drill bit
https://www.homedepot.com/p/Klein-Tools-201-Piece-Conical-Anchor-Kit-53729/100662394
