I removed the passenger seat, RV door and fridge doors and the old unit came out easily and new unit in.
It's all installed and running. I added an extra fan to the new unit (1210) and made sure all seams were sealed. I also added insulation to the coach cabinet.
The new to me unit tested good outside the RV. I'll try this unit and see what happens. All in all a fairly easy swap. I may get to do it again and install a residential. Time will tell.
PS. My plan B was to just swap doors if I couldn't get the old out. My old door gaskets were not good. The doors from the 1210 do not fit on the 1200.