2017-2021 6.6L L5P Duramax

You do not have a link list with a handle set to 2017-2021-6-6l-l5p-duramax, or you do and it's empty. Go ahead and create a link list called 2017-2021 6.6L L5P Duramax on your Navigation page and populate that link list with links that point to collections, to see collections listed here. Make sure the link list also has a handle set to 2017-2021-6-6l-l5p-duramax.