2020 Ford Expedition uses a spotlight with a PL length shaft mounted with a 189 installation kit for driver side mount or 189RH kit for passenger side. There are the number of shaft lengths because different vehicles may need different lengths for proper clearance through the vehicle and how far the light comes into the vehicle to avoid interfering with something in the cab, like steering wheel. We have been making these lights for 100 years and have had to add new shafts when existing ones did not work.