exhaust manifold stud

Hi guys I did some research for my sister on a used car and gave her the go ahead on this car. Problems it had was battery constantly dead because previous owner installed aftermarket radio and didn't ground it correctly or anything. It also needed a new catalytic converter so I replaced that. the previous owner actually had a new one but couldn't install it. I think this is because they tried and snapped two of the exhaust manifold studs off. I removed old manifold and put new one on but without those studs there is an annoying exhaust leak. I need to know what size they are so I can pull broken ones out and replace them any help is much appreciated.

if there is any room, with the manifold off, see if u can get 2 nuts on the stud, lock them in place, and use a wrench on the bottom of the 2 nuts to lock against the stop nut and u should be able to spin the stud out