I tend to agree that it's a 9". The 9-3/8" 3rd. member has (at least the ones I have seen) a downward curve to the topmost horizontal cast-in reinforcement rib. I once pulled one of these out of a hearse we had in our 'yard thinking it was a 9", spent the best part of a day digging a spider hole to work down under the damned thing (I was like 12 at the time). Finally got it out and hauled up to the shop. My Dad just shook his head.
The housing has two different ends on it: one earlier, one later.