On my Flagstaff 5th, there is a manual crank fitting on the opposite side of the trailer. Our slideout is on driver-side and the crank fitting is on the passenger side under the steps to the door.
Found the "general" location in my manual and then by a bit of poking around.
John & Deej
2003 GMC Sierra 3500 6.6 litre TurboDiesel
2011 Flagstaff 8528RKWS 5th