Parking light ground - 71 swinger

It's been a year now since i tore my 71 dart apart. It's on its way back together now. But, after a year, you kind of forget stuff. On the back of the parking light assembly there is a .250 tab that aparently grounds the parking light bulb. Is that true? If so, is there a separate lead that grounds the lamps? If so, where does that lead attach to ground?