Internally, the Fab 9 makes use of an axletube bulkhead (much like a Pro Stock housing). The bulkhead is a critical piece in the assembly since it anchors the axletube(s). Without the bulkhead, the strength of the assembly would be compromised. Keep this in mind when looking at other fabricated housings. By the way, Fab 9 housings are available in either mild steel or chrome moly.