That's just the problem-it doesn't seem like a bolt at all. The replacement caliper's top mounting hole, where a bolt would go, doesn't have threads, so it just seems like it should slide off but it won't. As far as I can tell from looking from inside the wheel well, there's no bolt in there. If I can't figure anything else out, I'll just take the bracket that holds the brake pads off too and maybe it has a bolt coming in from each side. Mine's a Gen1, but who knows!

85 Pickup, Desert tan spray job, 3" Rough Country lift, Marlin shackles+bumper, Chebby igniter, 33x10.5" BFG's