Congrats on the new camper. Tommie gave you some good information. Dometic fridges are in a bunch of different campers (my old Shasta, Prowler and now Sunline all had them) and in all sizes. You may want to check the space of the old fridge to make sure that everything is there(110v power outlet, propane gas line, 12V). All the ones I had could be powered the 3 ways so check the spec sheet vs your model to see what set up it was. When the tree went through the Shasta, I sold everything on ebay so I could recover my lost cash to work on a replacement. I made decent money and someone got a working unit without having to buy new so I would check to see what sizes fit your camper and start looking on ebay, local craigslist or on line for "used RV Parts Dometic".
Best of luck, keep us posted and always remember, we all love to see pictures of your camper.