Anyone know the thread size for the header stud? I want to replace the stud and nut with a bolt instead so that I can install my header when I put the engine back in. Anyone know any online shop that sells them?

 

just go to like autozone or a hardware store and get a double ended stud, take the old one with you to measure one close. or go to the deal and pay out the a$$.
just use the double nut method to put the new one in and some threadlocker

 

the size should be 10mm by 1.25 threading. And I believe it's about 1.5 inches....??? long