So, you won't find a large, rectangular box like you might on older cars. Instead, the rack and pinion assembly is located behind the front bumper, close to the steering column, and looks more like a long, cylindrical metal housing with internal gears. It will likely have various hydraulic lines and tie rods connected to it.
If you're looking for it on a specific year Caravan, searching online for "[Year] Dodge Caravan rack and pinion assembly diagram" will give you a visual of the component's location and general appearance.