If location is an issue, A/C units are not at all brand specific to Sunline. Many brands used the same A/C unit, like tire brands on a car. That said, used RV parts are fairly hard to find because there isn't much money in parting them out. Good luck with your search.
2007 T-286SR Cherry/Granola, #6236, original owner, current mileage: 9467.8 (as of 5/26/19)
1997 T-2653 Blue Denim, #5471
1979 12 1/2' MC, Beige & Avocado, #4639
Past Sunlines: '97 T-2653 #5089, '94 T-2251, '86 T-1550, '94 T-2363, '98 T-270SR