68 dart. how does the front turn signal parking lens get ground??

'68 Darts have a separate wire for each side that hooks to the 'tab' you see on the housing and that wire runs back to a bolt in the radiator support.
The wires normally have a push clip on one end and a looped end on the other.
They bolt to the core support and use a bolt that is the exact same diameter and appearance as the ones that hold the grille support tabs to the radiator support. The correct hole is in fact located near a grille support tab on each side.

Mark.