Question about 66 fog lights

Hey Guys,

I installed the fog light kit on my wifes 1966 Mustang last night. It looks really good! I am not concerned about the originality in the interior so I thought that I would just wire them up with a simple rocker switch. I wired them up the way I think that they should have gone (gray wire hot...black wire ground) but it blew the fuse immediately. Then, I remembered that originally when you flipped on the fog lights, the parking lights and tail lights came on with them. Now I am thinking that the fog lights themselves are grounded through the grille bolts and that I only need to hook up one of the wires to make them light up. Am I on the right track? Have any of you guys run into the same issue? I really want to get them up and running this evening. Any help is appreciated. Thanks.