In a message dated 7/27/2007 2:01:09 PM Central Daylight Time, 308gtsi at adelphia.net writes: > Seems like everything on my TR4a is fine thread pitch, so I'd buy > everything > from #6 up to 3/4 in fine pitch! > That's what I thought until I ran into coarse threads on my exhaust manifold. 3/8-18 Dave