Dick....Some of the Beaver and later, most of the Monacos used an inverted outlet at the rear of the fridge. They used the inverted outlet to run the icemaker. If you look behind your fridge (exterior door) check to see if you have two outlets and two plugs. If you do, one of them is inverted.
If you don't have an inverted plug, you can do what I did. I added a second 600 watt Magnum inverter and ran power to my new refer. This put the residential unit on it's own inverter. Even adding the inverter was cheaper than a new Norcold or Dometic.