Yeah I was thinkin 13mm or 1/2 couldn't quite tell feelin around in there haha. Thanks for the help men.
As for my tabs I actually found some 1/4" metal brackets that were about 8" long with 4 holes dead center. I think they were like 87cents a piece haha. Bent them accordingly and they fit extremely well actually! Lights will be nice and snug to the grille and the holes gave me a quick easy place for a ground point. Pics will come hopefully in the next few days here so everyone can see what they look like. Might be a cheap and easy route!
Fabtech spindles,AAL and Belltech 6400's, 35/12.50/15 General Grabbers, Richmond 4.56, Ford Racing Trac-Lok with kevlar clutches, 31 spline expo 8.8 with discs and welded tubes, 15x10 drifters, fx4 interior, Mcqueen Prototype hood/front bumper/front fenders/bedsides