Contour Enthusiasts Group Archives Forums General Troubleshooting exhaust manifold nut

I searched and had a bit of trouble finding the size of the nuts that hold the y-pipe to the rear ehaust manifold. Both nuts are rusted to s**t, but the studs on the manifold itself look ok. What size nut should I get to fit the studs, and will any nut work, or is there anything special about them I need to know. Thanks.