I am tearing down my 400. the manifold bolts in the center of the exhaust manifold have an odd looking bolt, where the head of the bolt is about the same diameter as the shank of it... what tool do you use to remove them?? there isn't a traditional 6 point or 12 point head on it. The motor is original and has never been worked on to this level, so the bolts are probably original to it. Thanks, Jay