SJH, as far as I can tell it does include the factory installed rear A/C. I have a Bighorn 3055RL, it was listed as 12' 11",,,, I had the front A/C installed. I measured mine with a board and level across the front a/c (highest point) and I am 13'2" hooked up and ready to roll. I have been under a few places at 13'6"...with no noise
and my a/c still works...so I guess I am OK.
Jim M