There's usually a hole on the opposite side of the trailer directly across from the slide out. If there is no hole to put the manual crank in to, check underneath that same area for a nut that the crank fits on to to turn.
2020 Silverado 2500HD LT, CC, 4X4 6.6 Duramax
2021 Grand Design Reflection 311BHS
I asked him to do one thing and he didn't do any of them.