Don't know where you are, but in the U.S., you can purchase
at a good hardware
store, because it's Marine, doesn't mean it's special, i just replace a heating element for a customer, purchased at a hardware
store, it's 700 watts, and powered by a Honda generator
, costs about $15.00. D C is not the way to go, as it pulls to much amperage. Never heard of a Diesel powered fridge, fridges that use a power source other than electrical
[AC or DC], have a flame, could be a wick or a pilot light type of source, the wick would be a Kerosene and a pilot light type would be Propane. Assuming you are not in the states, as we use 110 here, or maybe you are, if so you can replace the 220 with a 110, the tank will no the difference, and anyway if you are powering the unit with the Honda it's all mute.