I repaired mine a couple of years back when I hung the bumper cover on a parking stop.
I used really big pop-in type threaded nut things that came with a kit from Northern Tool.
The kit had a pair of pliers thingeys with threaded inserts, you screw the pop-in nut to the insert, place it in the hole, then when you compress the pliers the nut collar expands into the hole.
You then unscrew the insert and use whatever thread size bolt is appropriate.

Worked fine for me, results may vary for persons exhibiting less genius than I

tool :
http://www.ebay.com/itm/Hand-Nut-Riv...-/121665529812

video :