340 Exhaust Manifold Bolt

OOPS - just reread your post - 71 manifolds. Maybe they don't mount like this, but here's some pics of the earlier ones and the odd bolt in case yours is similar. I've never seen a stock exhaust on a small block without studs in the far end holes. Those studs go into the water jacket (don't forget to use thread sealer) and eliminate the need to drain the water before removing the manifold.