I took the top of the valve off and used a piece of 9/16 drill rod to replace the stem. It retains the original packing and you can just tighten the nut to keep it from leaking. Be sure to remove the packing before brazing or it gets real smokey and leaks. I sure this could be done with a carbon valve and skip the brazing part. The pilot bit on the real ones are bigger on the end and split so they retain the slug.