If that unit is a Dometic NXT, I got my third AC from the place below and installed myself. After you get the cover off, there's four lag bolts that hold it to the roof trusses. The wiring is right there in the 14x14 hole. Just swap thermostat and power connectors. I used my tractor front bucket to lift up to the roof, but there's other ways.
Here's a link:
https://www.rvpartscountry.com/searc...yword=nxt&www=
They dropped shipped the new unit from the closet Dometic warehouse in the country. The one they shipped from was in SoCal and I got it within two days.
If that's the front unit, you could spend $200 more and get the heat pump model as well. That's what I did so they are both ducted for heat and cooling.
You also have to match the simple thermostat vs CCC II control models as well.