The instructions are a bit worrying in their 1980s copier appearance.
The fan comes with a small gearbox to move the vent crank mechanism in a modern trailer.
Luckily, the holes for the vent crank lined up directly with the holes in the fan. This meant we needed an extension for the crank knob. We considered using a piece of plastic tubing or metal pipe, but in the end, we just took the gears out of the supplied mechanism, used the gearbox screws to bond them together and they fit perfectly, if a little hacky.
Reusing the high quality vent and trim that matches our windows is exactly the type of rebuild we are going for. It actually looks OK and works great. We will probably add some foam gasket material in the gap and add a PWM speed controller after we take it for a test run.