Today I replaced all my exhaust flange nuts with the 12 pt. reduced dimension steel nuts from Summit Racing. The inboard nut on the #2 cylinder was still a sonnuvagun to get started, and I can't torque it until I find a 12 pt. 3/8" swivel socket. Here are some of the nuts I've tried. From the height of the shadows, you can see that the 12 pt. nuts are taller. There was at least one thread showing beyond the nuts, though.