9 inch is the diameter of the ring gear and has nothing to do with the housing size. That looks like a 9 inch housing to me. That is the one with the long tapered center, which is the stronger one. It also looks like it may have the smaller 28 spline axles.
Cost us a fortune to do cars up in Australia I paid $400 for this housing now need to spend over 3grand on it
To get large bearings ends wilwood brakes and 35 spline axles and centre. .
Because we have to buy everything from usa.