That question is another "Depends"
What most folks fail to observe is the moisture vent on the microwave.. Now the old Tappin I had at my house vented to the front, many vent to the top, rear or side, if you take a microwave out and set it on the shelf and operate it with a load of water and run you hand around it you will feel the vent.
Or if you know what to look for you will see it
The Dometic in my rig was made by Lucky Goldstar, and thus did not work properly when new (I have fixed it) it vents to the top, Dometic put a special "Duct" on top to re-direct it out the front so that the cabinet it's mounted in does not rot out quickly.
You need to carefully remove the one you have, then look it over, if there is special duct work you will see it. Get a replacement that is the same physical size and vents in teh same manner, and transfer any speical duct work.
There is NOTHING special about the microwave itself, the Dometic unit in my rig is identical to an LG model in the store, save for that duct work and the mounting flange (Frame) Dometic put around it, all of which can be transferred.
NOTE: I Very strongly recommend AGAINST LG Microwaves.. As I said, being an LG it did not work properly when new.