@Smudge617
All I know is the first (and last) steamer I tried to remove the body of to do a DCC install fell apart and parts went every where, including the wheels and a lot of little bits and pieces. I swore - I would NEVER do another after that. I have also seen instructions for DCC installs and there seems to be a lot more to be removed. It might depend on the engine as well, or make, but one I looked at had you removing individual body parts, fire boxes, cabin, things down the sides, the boiler part and so forth.
As said, it might depend on the steamer or make, but from what I have seen - not as easy as just removing the trucks.