Hey guys, I've got a 69 302 in my 50 F-1 that I'm rebuilding, and I hit a snag replacing my broken exhaust manifolds with some 75 & 78 manifolds from a local yard.

The only bolt I had in my previous exhaust manifold only goes in about two threads depth before it locks up (I got four new bolts the same size/thread as the one old bolt that fit the old 69 manifold). The threads in the manifold appear to be in good shape visually, and look to be coarse thread.

Can any of you guys with these 70's era trucks find me the size/tpi of the bolt that connects the exhaust to the manifold?

Thanks,
Jim