he probably got some oddball car manifolds or even ones from a small block, big blocks aren't real common in the yards ... big block manifolds/headers fit big blocks, how they suit the particular vehicle is what counts ... there are variations in where they dump, some factory manifolds might interfere with fittings around the oil filter that varied among different vehicle models [like for oil coolers] or dump in the wrong place for a particular transmission, especially automatics, or bump a particular year/type of motor mount ... the headers fit any block and the huggers clear the mounts and are short enough you can route the head pipe any way you need to
Bill
