I recently pulled a 351 from a 85 Bronco and broke the studs off the manifolds that connect to the Y pipe. What is the best way to replace them?

 

On cast manifolds the studs are double ended, but because of the age, they are most likely rust welded to the manifold. To start with, soak it down with penetrating oil. I would try tapping them out first and then end up using an easy out. If all else fails, drill the studs out and retap.