It should be a standard 14 inch opening. Any fan will work. I’m partial to the maxx air fans with the built in rain cover. Just remove the old one, disconnect the wires and connect the new one and seal it according to the instructions.
2006 Damon Daybreak 3276 35'with 5 Star Tuner. 3 200 Amp Lithium batteries and 2000 watt PSW inverter/charger. 2013 Elantra on a Master Tow dolly.