I have a 68 Z/28 04A build and I want to know what type/size bolts were used to connect the exhaust pipe to the exhaust header outlet flange? My left side manifold (3872683 dated C18) has I believe are 3/8 coarse thread bolts, both going into the manifold and for attaching exhaust pipe. My right side manifold (3872730 dated D18) has, again I believe, 3/8 coarse thread going into the manifold but fine thread to attach exhaust pipe. Any known reason for this except that the right side has the heat riser?
Exhaust manifold flange studs and nuts were 3/8"-16 thread; if you found studs with 3/8"-24 (fine) threads, someone replaced the originals with the wrong studs.