I liked the idea of mounting a winch inside the frame behind the front bumper as I have seen some other people do to their trucks. My truck is a '72 K10, and I bought a Smittybilt X20 10000lb winch.
My first couple cardboard prototypes were poor designs that mounted to the bottom of the frame rail. My third prototype (which I ended up building) was the simplest design and mounts to the top of the frame rail. This allowed the winch to hang upside down and be mounted as high up as possible. It also allows the fairlead to come out of the middle of the bumper instead of the bottom. I just had to clock the clutch housing so that the handle was pointing forward instead of down.