My self-locking nuts were a mission to take off, I had to use an impact wrench and a impact chisel. Any way, one was so tight that the entire stud came out of the block and the sutd is damaged. Do I really need to use all 9 nuts, or can I use a regular bolt with a locking washer to replace the damaged stud?

Thanks guys

 

you can try to use that, but if the header doesn't seal with the gasket your going to have an exhaust leak and burn up your exhaust valves.