I just took mine out of our 61 Overlander. I started by turning off the propane tanks. I then took off the shroud or cover, mine had 4 screws. There were about 6 or 8 screws holding the unit to the cabinets, remove these. I then disconnected the propane connector at the bottom of the unit near the thermostat control. I cut of the the treaded nipple then push the copper tube through the bottom the the trailer. I then disconnected the vent on top the trailer and pull the vent pipe up through the top of the trailer. There were 2 scews holding this on. I then pulled the whole unit out of the cabinet, it was a tight fit.
I now have to seal up the top where the vent pipe was with some Aluminum, vulkum and rivets. This will have a nice clean look. Now most importantly I have to go under the trailer and cap off the propane line that went to the heater. I'm going to replace it from the main line while I'm there.
That's as far as I got, I hope I did not leave anything out! Check out all the other threads they are extremely helpful and come from people with more experience than me.