im not sure what you are asking in the second question, but there are three cast iron housings in a rotary (front, intermediate, and rear), but im sure you knew this. and about the housings, call mazdatrix and ask them. theyre awesome and three hours behind so theyre open late. i think the dif is that the s4 is a 4 port and the s5 is a six port, but id call and ask anyway...

the number is 1-562-426-7960