im not positive but i think the housings are different from /6 904 to sb 904 the guy who i bought my car from converted /6 to 318 and had to have the housing switched.
I do have a SB 904 (Thanks Muller) stashed away that I have been debating using, looksmlike the decision has been finalized. I was leaning towards the 727, just because it only has 30 some thousand miles on it.