Anyone know what bolt size this is? Or do I have to buy a new exhaust manifold to get the specific bolt.

 

Take out one of the other ones if need be and go to a store and get the matching bolt.

 

Didn't wanna snap the bolts but it decided to come off just using my fingers. Previous owner did not tighten the bolts down im assuming. But yeah manage to snag my self 16mm drain bolts from ace hardware. Fits like its the old one. All good to daily again.