Question for rustyratrod. Didn't the original manifolds from the sixties use a 5/16 bolt in the center hole closest to the engine. Also would like your opinion on 1972 Dodge TSB section 11 on exhaust manifold replacement found in the Hamtramck registry.
All I've ever seen had a 3/8 stud there. That sure as HECK doesn't mean that's all they ever used, cause I ain't seen it all. lol Can you post a link to the Hamtrack?