Sometimes you just need to step up the program and use a big old Hex Cap (3/8-16). These babies have got the heft that you are looking for in hot dipped galvanized so it will be able to resist corrosion. Great for applications where corrosion is not the end of the world but strength is important. Galvanized is the least expensive of the non-corrosive fasteners. These Hex Caps do not include nuts.