The heigth depends on when it was built. We used a Carrier A/C unit and the height to the top of the A/C on a 31RED would have been 9'10"... But last spring say March 2010, Carrier went out of the Trailer A/C business and we switched to a Dometic A/C which was a tad taller, so anything product for about a year will be 10'2" on the small slide models....The King Slides the units are a bit taller at 10'10"