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.
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.