Front Body Mount Bolts

Where can I get longer front body mount bolts for an 02' Durango 4 door. I am installing nerf bars and want to drop the front a little to get them even with the body and rear mount. The factory bolts are 3-1/2" long, I would probably use a 4 or 4-1/2" if I could get them somewhere. I do not know the diameter or thread pitch can anyone help me out.