Hi-po exhaust manifolds
As above, there you go! Use them under all the bolt heads and nuts that they fit under. The sleeve nuts themselves provide a wider bearing surface on the manifold than bolt heads or regular nuts. I have never used the sleeve nuts in the form of studs and then sleeve nuts. When I got my bolt kits the extra studs were already loctited in the sleeve nuts so that they looked like long fat bolts with threads sticking out of the bottom. It's already a chore to get the manifolds on with the far end studs in place without adding even more to maneuver around.