Joker,
I just looked up the Big Sucker kit in two catalogs, seems you are looking for one of the smaller drilled bolts for the vent,rather than the mounting studs for the backplate that I thought. My mistake. Seems I did not save the install instructions for this kit, but if you still have it and it has the Ness part number, they should help you get a replacement. If not post the part number here and one of us 'locals can go up and brow beat them a bit, they're about 30 minutes from the house. I still have the stock banjo bolts I removed, but as GRC says they a bit different than stock H-D.